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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

VIDEO TUTORIAL: HOW TO MAKE GUINNESS BROWNIES

LET’S TALK FLAVOR + TEXTURE

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 brownies, these Guinness brownies are not particularly chewy. They taste like fudge. A square of dark chocolate fudge.

HOW IT WORKS

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

FROSTING

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

Description

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


Ingredients

Scale
  • 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

Instructions

  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.

Notes

  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 live at 5300 ft elevation. Is there an altitude adjustment to the recipe? Thank you

    1. Hi Lori, I wish we could help, but have no experience baking at high altitude. Some readers have found this chart helpful: https://www.kingarthurflour.com/learn/high-altitude-baking.html

      1. I made the recipe with great success with these small alterations. I added 1 tablespoon of flour and 12 minutes to cooking time. It’s possible that a higher temperature would also have made the recipe come out right.

    2. Thanks for the tip, Lori. I’m making these right now at 5280 elevation and I will follow your instruction.

  2. Great recipe!! I was lazy and used my favorite box brownies adding melted butter (instead of veg. oil), 1 tsp. espresso powder, and 1/4 c. reduced Guinness (since my box only needed that much liquid. I made the frosting per your instructions.. OMG…these were delish! Thank you!

  3. I made these for my Guiness loving BF. He ate 3 brownies in one sitting. He commented that the frosting is the same color as the head on top of the Guiness when poured in a glass. My brownies were done in 30 minutes and were cakey, not like fudgy, so I was happy. Not very sweet so the frosting enhanced the brownie. BF said he’s going to eat the next piece with a glass of Guiness instead of milk.

  4. These were svery delicious. My hisbnd said they are a winner, I never had had Guiness before so I will either have to drink 5 bottles or make 5 more pans of brownies. I used an 8 x 8 pan and they took about 40 minutes.

  5. Best brownies I ever made … EVER … seriously! These are phenomenal. I don’t drink beer let alone Guinness, but something made me grab a six pack of Guinness Extra Stout, and I’m sure glad I did. The combination of the reduced Guinness and the espresso powder is an unbelievable combination. I made no adjustments in ingredients or baking time. These baked up exactly as shown in the recipe. The best part … my husband won’t touch the Guinness, so it is ALL mine for more baking! Thank you, Sally, for the perfect recipe.

  6. Never expected to love these as much as I do! “Inherited” two bottles of Guiness and this was the best use ever. Fudgy but not goopy, great texture, reduced Guiness and espresso powder add great depth of flavor. I halved the frosting as I wanted more of a sweet glaze rather than full out frosting. Thank you for another great keeper!

  7. These are delish! How do you freeze a frosted brownie without smashing the frosting? And if I wait to frost, can the frosting stay in the fridge and for how long?

    Thanks!

    1. Hi Alyssa, We are happy you enjoy them! You can either freeze them in a container where the frosting isn’t right against the lid. Or you can freeze them uncovered for 15-30 minutes until the frosting is “set” and then wrap them for a longer freezing time.

  8. Oh my gosh! Just made these for St Patrick’s Day, the best brownies ever♥️

  9. Really great recipe- including the frosting which I don’t normally bother with. Half the frosting was perfect for a lighter frosting contingent. Don’t skip the espresso powder in the brownies or frosting!

  10. I just made these for St. Patrick’s Day and they are delicious. I don’t normally like frosting, but the frosting was a nice addition to the brownie. They are equally as delicious without the frosting. This recipe is a keeper and not just for St. Patricks Day! 😉

  11. Made these for my St. Patrick’s day ladies bridge party. I never expected them to be so good since I am not a beer drinker. Huge success. I made several days ago and froze, and they tasted better than the day I made them. Definitely 5 stars!

  12. These brownies were easy to throw together and were very delicious, BUT…I took them out of the oven after 36 minutes—when the toothpick came out with crumbs as described, and the top seemed done. No settling occurred after they cooled so I went ahead and frosted them. The first three pieces were perfect (though for my taste, there was too much frosting—we loved the taste of the frosting), but beyond the first row, the brownies looked like raw brownie dough. It was the strangest thing. I was going to toss the whole pan, but then thought, what do I have to loose? I scraped most of the frosting off, and baked them for 30 more minutes and they were finally done. I tossed the frosting and the frosting that I couldn’t scrape off baked and looks like of cool and added a tasty sweet topping. I dont think I will make these again unless I add more flour and bake at a higher temperature.

    1. Hi Stacey! You can double this recipe for a 9×13 inch pan. I’m unsure of the exact bake time.

  13. Made these for St Patrick’s Day & everyone loved them! Guinness flavour was subtle, complementing the dark chocolate I used perfectly (I prefer ‘less sweet’ so dark chocolate was perfect). Didn’t have espresso powder so substituted Kahlua liqueur for a bit of the condensed Guinness in both the batter & icing to give that coffee flavour. Worked perfectly! Thank you for the recipe

  14. I made these for St. Patrick’s Day this year and they were a huge hit with my family. We have some beloved brownie recipes already, but judging from the response I got, these brownies will be at the top of the list. I doubled the recipe and it worked out great. The espresso powder really added to the flavor. Thanks Sally!

  15. Super delicious – was nervous at first. My beer reduced down too much within 12 minutes, so I only had 1/2 cup. I used an oatmeal stout from Trader Joe’s. Since I didn’t have beer for the frosting, I used Bailey’s Irish Cream. I will note, I halved the frosting and felt that was enough for the pan. Especially since we got a lotttttta buttttah in the batter.

    Would certainly make these again, maybe omit the espresso powder from the frosting and add a bit more to the batter.

    Do I keep these in the fridge?

    1. Hi Kate, We are so happy you enjoyed these! We usually cover the brownies and store them at room temperature for up to a week but you can certainly store them in the refrigerator also.

  16. I made these brownies a week ago and they were great. Has anyone had experience with bake time if you double the recipe, and use a 9 x 13″ pan?

  17. Hey there! I wanna make these but all I have is cocoa powder. What would be the best ratio for that?

    1. Hi Meg, you really need pure chocolate for this brownies recipe – it yields the best flavor!

  18. I was definitely skeptical about the taste of the Guinness, but you have to trust the process with this one. SO delicious, they taste like bars of fudge. Thanks for the recipe : )

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