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Guinness brownies with icing stacked next to a can of beer.
5 from 1 vote

Dark Chocolate Guinness Brownies With Buttercream

Prep Time: 25 mins
Cook Time: 35 mins
Cooling Time: 2 hrs
Total Time: 3 hrs
Servings: 12 brownies
Author: Bailey
These Guinness brownies are topped with a quick homemade buttercream and filled with dark chocolate, and stout beer flavor.
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  • ½ cup butter unsalted
  • 6 ounces dark chocolate bakers chocolate, 2 bars
  • 1 ½ cups granulated sugar
  • 12 ounces Guinness beer 1 bottle, or can
  • 1 teaspoon vanilla
  • 3 eggs
  • ½ teaspoon espresso powder
  • 1 cup flour


  • ½ cup butter softened
  • 2 cups powdered sugar
  • ½ teaspoon espresso powder


  • Preheat oven to 350°F. Grease and flour a 9x9" baking dish.
  • Pour Guinness into a saucepan over high heat. Reduce until 2/3 cup remains, 10-12 minutes. Pour Guinness reduction into a heat safe liquid measuring cup to cool for at least 15 minutes.
  • Meanwhile, add dark chocolate and butter to a medium microwave safe bowl. Melt in 30 second increments, stirring between each one until mixture is smooth. Stir in sugar, eggs, vanilla, and ½ cup of the Guinness reduction. Add salt and flour, mixing until just combined without overmixing. Batter will be thick.
  • Pour batter into prepared baking dish. Bake for 30-35 minutes, or until a toothpick comes out with wet crumbs (not batter). If toothpick has batter, return to the oven and cook with 3 minute increments until wet crumbs are achieved. Cool brownies on a wire rack for at least 2 hours until fully cooled.
  • Meanwhile, for the buttercream, beat softened butter until fully creamed and no lumps remain using a stand mixer or hand mixer. Add powdered sugar and espresso powder, and mix until smooth (it will be thick and dense). Add remaining Guinness reduction, a tablespoon at a time, until buttercream becomes light and fluffy.
  • Frost brownies with prepared buttercream, then cut into squares.


You can omit the espresso powder in the batter and buttercream, if desired.
For fudgier brownies, reduce the amount of flour added to ¾ cup.
Calories: 545kcal | Carbohydrates: 67g | Protein: 5g | Fat: 29g | Saturated Fat: 17g | Trans Fat: 1g | Cholesterol: 82mg | Sodium: 157mg | Potassium: 238mg | Fiber: 3g | Sugar: 51g | Vitamin A: 543IU | Calcium: 34mg | Iron: 4mg