Description
These frosted sugar cookie bars are soft, chewy, buttery, and topped with a thick layer of creamy vanilla buttercream frosting and colorful sprinkles. No dough chilling, rolling pin, or cookie cutters required.
Ingredients
- 1 and 1/2 cups (188g) all-purpose flour (spooned & leveled)
- 1 teaspoon baking powder
- 1/4 teaspoon baking soda
- 1 and 1/2 teaspoons cornstarch
- 1/4 teaspoon salt
- 1/2 cup (8 Tbsp; 113g) unsalted butter, softened to room temperature
- 3/4 cup (150g) granulated sugar
- 1 large egg + 1 egg yolk, at room temperature
- 2 teaspoons pure vanilla extract
- 1/4 teaspoon almond extract (optional)
- 6 Tablespoons (60g) rainbow sprinkles (not nonpareils)*
Vanilla Buttercream
- 3/4 cup (12 Tbsp; 170g) unsalted butter, softened to room temperature
- 2 and 1/4 cups (270g) confectioners’ sugar
- 3 Tablespoons (45ml) heavy cream or half-and-half*
- 1 teaspoon pure vanilla extract
- pinch of salt, to taste
- optional: gel food coloring (I used 1 drop red) and extra sprinkles
Instructions
- Make the bars: Preheat oven to 350°F (177°C). Line a 9-inch square pan or an 8-inch square pan with parchment paper, making sure to leave enough overhang on the sides. I use and prefer a 9-inch square pan. Set aside.
- In a medium bowl, whisk together the flour, baking powder, baking soda, cornstarch, and salt. Set aside.
- In a large bowl using a handheld mixer or stand mixer fitted with a paddle attachment, beat the butter and sugar together on medium-high speed until light and fluffy, about 3 minutes. Scrape down the sides and bottom of the bowl as needed. Beat in egg, egg yolk, vanilla, and almond extract (if using). Scrape down the sides and bottom of the bowl as needed.
- Add the dry ingredients to the bowl with the wet ingredients and beat on low speed until mostly incorporated, then increase to medium-high speed and beat until completely combined. The dough is thick and sticky. Finally, beat in the rainbow sprinkles.
- Press the cookie dough evenly into the prepared baking pan as best you can. Use a spatula or lightly floured hands to press evenly; it will seem like a thin layer of dough.
- Bake for 25–26 minutes or until very lightly browned around the edges. The center will still look very soft, that’s OK; the bars will continue to set as they cool. Do not over-bake.
- Allow the bars to cool completely in the pan set on a cooling rack. The center will slightly sink—that’s expected.
- Make the frosting: With a handheld or stand mixer fitted with a paddle attachment, beat the butter on medium speed until creamy, about 2 minutes. Add confectioners’ sugar, cream, and vanilla extract and beat on low speed for 30 seconds, then increase to medium-high speed and beat for 3 full minutes. Stop the mixer and scrape down the sides of the bowl as needed. Add more confectioners’ sugar if frosting is too thin or more cream if frosting is too thick. Taste; beat in a pinch of salt if the frosting is too sweet. Beat in food coloring, if using.
- Lift the cooled bars out of the pan by gripping the parchment paper overhang; transfer to a cutting board. Spread the frosting over the bars and decorate with extra sprinkles if desired. Cut into squares. Use a very sharp knife and wipe the knife between each cut for neat slices. Store bars in an airtight container at room temperature for up to 2 days or in the refrigerator for up to 5 days.
Notes
- Make Ahead Instructions: You can make these bars and the frosting 1 day in advance. Store the bars, covered, at room temperature overnight and store the frosting, covered, in the refrigerator. Bring the frosting to room temperature and give it a quick mix before using.
- Freezing Instructions: You can also freeze the frosted or unfrosted bars for up to 3 months. Thaw overnight in the refrigerator, frost if needed, cut, and serve.
- Special Tools (affiliate links): 9-inch Square Pan (preferred) or 8-inch Square Pan | Electric Mixer (Handheld or Stand) | Glass Mixing Bowl | Whisk | Silicone Spatula | Cooling Rack
- Cornstarch: Just a small amount of cornstarch helps create an exceptionally tender sugar cookie bar. It keeps the cookie bars soft without making them cakey. If you don’t have any, you can simply leave it out.
- Extra Egg Yolk: 1 egg binds everything together and 1 additional egg yolk adds richness, moisture, and chewiness. Do not skip.
- Sprinkles: Use regular rainbow sprinkles (aka “jimmies”) in the cookie bar base. Nonpareils (the little balls) will bleed their color in the dough. Save those for the topping, if desired.
- Cream: Cream or half-and-half makes for the creamiest, fluffiest frosting, but whole milk also works.
- Larger Batch: You can double this recipe and bake in a 9×13-inch pan; the bake time is about 35–40 minutes.
- Update in 2026: This recipe used to call for 1/2 teaspoon of baking soda but over the years, I have found that is simply too much. Use 1/4 teaspoon baking soda as instructed above, plus the 1 teaspoon baking powder. We also reduced the sprinkles from 1/2 cup (80g) to 6 Tablespoons (60g), and updated the bake time to help ensure the bars turn out soft and chewy, rather than dry.