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Guinness brownies cut into squares with Guinness frosting

I asked readers about St. Patrick’s Day dessert recipe requests recently. The outpouring of “anything with Guinness” convinced me to pick up a 6 pack and begin recipe testing. My kitchen smelled like a brewery at 9am on a Tuesday morning, but the result was well worth my boozy wake up call.

Before you run away at the thought of beer brownies, let me explain. These Guinness brownies do NOT taste like beer. Guinness stout, with its roast coffee and caramelized flavors, is often paired with chocolate in baking. They’re a natural duo because Guinness not only intensifies chocolate, but adds a malty background.

A quick internet search for “Guinness brownies” will spew out a million results. Even still, I wanted to try my hand at this popular dessert because even though brownies seem pretty basic, it’s difficult to maintain a desirable texture when you begin adding all sorts of stuff. And I was ready for the challenge.

stack of 3 Guinness brownies

Guinness beer bottle



Dark chocolate comes to mind first. These Guinness brownies aren’t overly sweet, so you’ll find yourself grabbing another. (If it’s not the brownies that are addicting, it’s the frosting. More on that below!) If we’re talking texture, they’re very dense and very moist. In fact, they’re the moistest brownies I’ve ever baked… because they’re the only brownies I’ve ever baked with Guinness! Unlike my chewy fudgy homemade brownies, these Guinness brownies are not particularly chewy. They taste like fudge. A square of dark chocolate fudge.


To impart enough flavor into the brownies, we’d have to use a lot of beer. But adding liquid to brownies makes absolutely no sense. So let’s take what we learned from homemade strawberry cake and reduce the beer down on the stovetop first. The heat evaporates the liquid, but leaves the flavor. Little liquid, lots of flavor, won’t turn our brownies into cake. We also do this with champagne in mimosa cupcakes. And I do the same thing with my Guinness chocolate cupcakes, too!

This step is really easy and requires zero effort from you. Pour an entire 12 oz bottle of Guinness into a saucepan. (The whole bottle! Nothing to waste!) Leave it alone to simmer for 20ish minutes, until it’s reduced down to 2/3 cup. This is less than half the liquid we started with, but triple the flavor.

We’ll use 1/2 cup of reduced Guinness in the brownie batter and the remaining 2 and 1/2 Tablespoons in the frosting.

reduced Guinness in a glass measuring cup

The rest of the brownie ingredients are usual suspects. Butter, sugar, eggs, flour. Instead of cocoa powder, we’re using pure solid chocolate. Sometimes I use a combination of pure chocolate AND cocoa powder in homemade brownies, but I wanted to keep things really simple since we’re taking extra time to reduce beer on the stove.

Besides Guinness, you know what else intensifies chocolate’s flavor? Coffee. I add espresso powder to both the brownie batter and frosting on top. It’s optional, but if you really want a deep dark chocolate brownie, don’t leave the espresso powder out.

pouring brownie batter into baking pan


The brownies are great alone, but better with this frosting. Their decadent nature screams for something creamy! (That being said, eat one with a pint of Guinness in the other hand.)

This caramel colored frosting is an interesting flavor. Interesting in a good way! It’s mostly espresso flavored, though there are lingering notes of maple too. Not sure how it tastes like maple, but I suspect it’s the combination of reduced Guinness, vanilla, and confectioners’ sugar. Whatever the reason, it’s SO GOOD because it’s SO DIFFERENT.

Guinness brownies cut into squares with Guinness frosting

Guinness brownies cut into squares with Guinness frosting

You might also love my Baileys and coffee cupcakes and shamrock cookies too!

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Guinness brownies cut into squares with Guinness frosting

Guinness Brownies

  • Author: Sally
  • Prep Time: 45 minutes
  • Cook Time: 35 minutes
  • Total Time: 3 hours
  • Yield: 1620 brownies 1x
  • Category: Brownies
  • Method: Baking
  • Cuisine: American


These Guinness brownies are made from reduced Guinness Stout. They’re fudgy, rich, and topped with espresso powder and Guinness infused frosting!


  • one 12-ounce bottle Guinness Extra Stout
  • 3/4 cup (12 Tbsp; 175g) unsalted butter
  • two 4-ounce bars (226g) semi-sweet chocolate, coarsely chopped*
  • 1 and 1/4 cups (250g) granulated sugar
  • 3 large eggs
  • 1 teaspoon pure vanilla extract
  • 1 cup (125g) all-purpose flour (spoon & leveled)
  • 1/2 teaspoon salt
  • optional: 1/2 teaspoon espresso powder

Guinness Frosting

  • 1/2 cup (1 stick; 115g) unsalted butter, softened to room temperature
  • 2 cups (240g) confectioners’ sugar
  • 23 Tablespoons reduced Guinness (from step 1)
  • 1 teaspoon espresso powder
  • 1/2 teaspoon pure vanilla extract
  • 1/4 teaspoon salt


  1. In a small saucepan, bring the Guinness to a boil over medium-high heat. Once boiling, reduce to medium heat and allow to simmer until reduced down to 2/3 cup, about 20-22 minutes. Set aside to cool for at least 10 minutes. You will use 1/2 cup in the brownies and the rest in the frosting.
  2. Preheat the oven to 350°F (177°C) and grease a 9×9 inch pan or line with aluminum foil or parchment paper, leaving an overhang on the sides to lift the finished brownies out (makes cutting easier!). Set aside.
  3. Place the butter and chopped chocolate in a large microwave-safe bowl. Melt in 30 second increments, whisking after each, until completely smooth. Whisk in the sugar and 1/2 cup of reduced Guinness until completely combined. Whisk in the eggs and vanilla extract. Finally, whisk in the flour, salt, and espresso powder (if using). The batter will be thick and shiny. Pour/spread evenly into prepared pan.
  4. Bake for 32 minutes, then test the brownies with a toothpick. Insert it into the center of the pan. If it comes out with wet batter, the brownies are not done. If there are only a few moist crumbs, the brownies are done. Keep checking every 2 minutes until you have moist crumbs. My brownies take about 35 minutes.
  5. Remove from the oven and place on a wire rack to cool completely before frosting or cutting into squares.
  6. Make the frosting: In a large bowl using a handheld or stand mixer fitted with a whisk attachment, beat the butter on high speed until completely smooth and creamy, about 2-3 minutes. Add the confectioners’ sugar, beating on low at first then increasing to high speed. Once creamy and combined, beat in 2 Tablespoons of reduced Guinness, the espresso powder, vanilla extract, and salt. Taste. Add the remaining reduced Guinness if needed. If you want the frosting a little thinner, add a splash of milk.
  7. Frost cooled brownies.
  8. Cover and store leftover brownies at room temperature for up to 1 week.


  1. Make Ahead Instructions: Freeze frosted or unfrosted brownies up to 3 months. Thaw overnight in the refrigerator then bring to room temperature before serving.
  2. Special Tools: KitchenAid Hand Mixer | Glass Mixing Bowls | Saucepan | 9×9 Baking Pan | Icing Spatula
  3. Chocolate: You can find 4 ounce chocolate baking bars in the baking aisle. I like using Ghirardelli or Baker’s brand. You can use 8 ounces (heaping 1 and 1/3 cups) of quality chocolate chips instead, such as Ghirardelli brand.

Keywords: Guinness brownies

Reader Questions and Reviews

  1. I made these last night, but dairy free and they still turned out great! The Guinness took longer to reduce also because I live above 7000 feet.

  2. HI Sally -What would you say is the baking time for an 8X8 brownie pan instead of 9X9? I’ve had great success with your recipes; this one is my agenda for tomorrow!!

    1. Hi Shannon! They’ll take awhile in a smaller pan. I’m unsure of that exact time, but use a toothpick to test for doneness. A few moist crumbs are OK, but no wet batter.

  3. Hi Sally, is the espresso powder the instant type or just ground coffee powder? Thanks!

  4. Just finished making these. Amazing! I didn’t have espresso powder and these are still in the top brownies I’ve ever eaten. My coworkers are in for a treat tomorrow!

  5. My daughter and I made these last night and the are wonderful!  And the looked just like your photographs!  Thanks!

  6. Wow! I made these today and they are insanely good! I was one of the people who begged for a Guinness brownie recipe a few weeks back. This has definitely replaced my former one (as I thought it would). The texture of these brownies is unreal. What really set it apart for me was the Guinness buttercream. This will go on the St. Patrick’s Day tradition list for sure. Thank you so much for this recipe! Also (for people who read comments for tips) I used an 8×8 pan (it is all I have) and it took around 45 minutes. I started checking at 35. I like ultra thick brownies so this was perfect!

  7. I just made these for a St Paddy’s Day party tomorrow. I want to just eat them all right now! So so good. Thank you Sally for all your great recipes! 🙂

  8. OK, these are the BEST brownies I have ever had. My husband liked them so much that he took half the pan of brownies with him to share with a couple teachers at his school. The frosting was fabulous. I will bake these even when it’s not St. Patrick’s Day!

  9. I am making these as we speak, they smell AMAZING! I’m making the frosting and it looks runny (however is tastes delicious!!), any idea what I did wrong? 

    1. Perhaps the butter is a little too soft? No worries there, it should still be great. How does it taste today?

  10. Sally!  Delicious brownies!  We had them tonight after my Irish dinner (boiled corned beef..trick, press meat when it comes out of water), roasted potatoes and carrots, sautéed cabbage and leeks, and homemade whole wheat Irish Soda Bread!  Yummy St. Patrick’s Day!

  11. Made this for St Patrick’s Day. The frosting was to die for! Absolutely delicious the next day as well. Thanks for the great recipe, Sally!

  12. Best brownie recipe I’ve ever made. Weighed all ingredients & followed your recipe to the letter.  Also appreciated your link to an explanation of why careful measuring is key to successful baked goods. Again, these are fantastic! Thank you!

  13. Absolutely delicious! I made these yesterday for St. Pattys Day and my family loved them They are definitely a keeper!

  14. Made these today… wow!! So fudgy and delicious.  Will be making this again for sure! 

  15. I have made these brownies twice and they are delicious. I made them once for a St. Patrick’s day event at work and one for a St. Patrick’s Day dinner.

    I had one question though, the frosting after it sits for a bit gets white dots. I’ve made them twice and it happened both times. I thought maybe it was the salt but not sure. Have you run into this before? I use the recipe for the frosting exactly as stated.

  16. These brownies were fabulous! The tip to line the pan (I used foil) made it so easy to lift them out and divide in half – brought half to a friend’s home on St. Patrick’s day and the other half to lunch the next day at our daughter’s. Everyone loved them. Definitely a keeper

  17. You were right about needing to make two batches! I made these last night and they are already gone! My family was a little bit skeptical about them tasting too much like beer, but they LOVED them! These brownies are so moist, fluffy, AND fudgey! Didn’t know it was possible to have all of these textures at once, but it is! And it is fantastic. Definitely going to make them again- they are truly a unique and wonderful treat!

  18. I just made theses brownies and they are really tasty for breakfast!  My taster had to give his opinion on the frosting as I ran out of icing sugar after the stores were closed.  They tasted fabulous naked. So unctuous and rich!!  With this frosting, my colleagues are going to be in for a treat.  You have set my reputation with the Irish car bomb cupcakes and this will really give me star power now.  Thanks Sally. 

  19. Made these brownies for my coworker’s birthday this week and EVERYONE raved about them! The brownie part had me worried a bit because the batter looked thin after I mixed it up… and during baking it developed a weirdly cracked top but my oven sucks so it could be at fault. The icing definitely put it over the top! I had some left over so I made a couple of plain vanilla cupcakes (four, to be exact) and my fiance and I devoured them, lol. A keeper, without a doubt!

  20. Good-morning Sally, I have a confession to make, have made so many of your recipes and have received rave reviews from family and friends; sometimes I think I should tell everyone it is thanks to Sally too LOL. My question – I have made these brownies countless times and they are the best. I prefer a « cakey » brownie, do you think I could add baking powder to the mix?

    1. Hi Lucille! Thank you so much for baking and trusting my recipes. I appreciate it so much. Baking powder would certainly lift the crumb to yield a cakey Guinness brownie. Let me know how they turn out.

      1. This might be a crazy question- but does the expresso powder have to instant or can I use the expresso powder I would put in my coffee pot?

  21. I have one question. Since the beer was reduced on the stove, would the frosting not be alcoholic? I want to send some of these with my husband to work, but I don’t want him sharing these with his coworkers and getting in trouble.

    1. If you heat it long enough the alcohol will evaporate, but please do your research and make the best decision for you!

  22. Hey Sally,
    I was hoping to make these for a St. Patrick’s Day party and wanted to double the recipe so I would have enough. I was thinking of using a 9″x13″ pan and increasing the baking time somewhat. Have you tried this before?

  23. Hi Sally! These are SO GOOD–they have replaced the Chocolate Stout Cupcakes from King Arthur Flour as my go-to recipe for a chocolate item that’s out of the ordinary. While I liked thos cupcakes I never felt that the chocolate flavor was very intense. I do still use the chocolate stout though instead of Guinness–sort of a specialty item, I guess, but I’ve always been able to get it at a regular liquor store–the brand I always find is Young’s Double Chocolate Stout. The cans are 14 ounces, so I just boil it down to the amount you say-even more flavor! And what a genius, genius idea to boil it down in the first place. Also, b/c I usually am making these for a reception or party, I make them in min-muffin tins, baking them for about 15 minutes. I doubled your recipe and that made 96. And the frosting is genius too!

  24. I bought a 22oz of Guinness. When I make the brownies, I will still have another 12 oz, I really don’t want it to go to waste. Do you think if I reduced the other half, do you think it would keep in the fridge? Or should I just keep the bottle in the fridge and reduce it another time?

    1. Hi Madeline! You can store extra reduced beer in the refrigerator. Not exactly sure how long, but a few days would be fine!

  25. Didn’t have a 9×9 so went with a 7×11 since it was only 3 extra square inches. Bake time was the same. These turned out perfectly, although I admit using regular stout by accident (forgot to check for extra stout). Mmmm. Great treat to kick off the St. Patrick’s Day weekend at work!

  26. This recipe was outstanding. I think the tip to boil down the stout is genious! BTW, quite by accident, I boiled down 14.5 OZ of stout, not the 12 OZ you called for. Might have intensified the flavor, but this was for the better! First time using your site, and will be following more of your recipes in the future.

  27. Best brownies I ever made (including my mother’s go-to version). Very rich and creamy with a rich, bittersweet edge. I made them for a St. Patrick’s party and they were a crowd favorite.

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