Guinness Brownies with Frosting

Warm, fudgy, and quietly boozy, these Guinness Brownies with Frosting bring the deep malt and roasted notes of stout into a rich chocolate treat. The brownie base is dense and glossy, with a tender, almost truffle-like interior and a thin crackly top. The frosting is silky and balanced, carrying a subtle Guinness lift and a hint of espresso that intensifies the chocolate flavor without overpowering the sweetness. Aromas of dark chocolate, toasted barley, and a touch of coffee make these perfect for a chilly evening or a celebratory dessert. Serve them at casual dinner parties, with coffee after brunch, or wrapped as a thoughtful edible gift. If you like deeply flavored brownies with a grown up twist, these are a must-try. For a cozy pairing, try a cup of strong coffee or a small glass of the same stout you used for the recipe, and enjoy the contrast of warm, dense brownie and cool, creamy frosting. You might also enjoy a simple weeknight meal companion like an easy homemade pasta dish before dessert.

Ingredients

11.2–12-ounce bottle Guinness Draught Stout beer, reduced
Reduce the beer to concentrate flavor and remove some carbonation, leaving the stout’s roasted, malty character.
3/4 cup unsalted butter for brownie base
Butter provides richness and a glossy texture in the baked brownie.
8 ounces semi-sweet chocolate, coarsely chopped
Coarsely chopped chocolate melts into the butter for a deep, fudgy chocolate base.
1 and 1/4 cups granulated sugar
Sweetens the batter and helps create the thin, crackly top.
3 large eggs, at room temperature
Eggs give structure, moisture, and a tender crumb when room temperature.
1 teaspoon pure vanilla extract
Enhances the chocolate flavor with a hint of warmth.
1 cup all-purpose flour
Provides structure; measure gently to avoid dense brownies.
1/2 teaspoon salt
Balances sweetness and brightens the chocolate.
1/2 teaspoon espresso powder (optional)
Intensifies chocolate notes; optional but recommended for depth.

Frosting

1/2 cup unsalted butter, softened for frosting
Softened butter creates a creamy, spreadable frosting.
2 cups confectioners’ sugar
Confectioners sugar sweetens and gives the frosting a smooth texture.
2–3 tablespoons reduced Guinness for frosting
Adds a subtle stout flavor and thins the frosting to the right consistency.
1 teaspoon espresso powder for frosting
A small boost of coffee flavor to complement the chocolate and stout.
1/2 teaspoon pure vanilla extract for frosting
Rounds and deepens the frosting flavor.
1/4 teaspoon salt for frosting
Small amount to balance sweetness and sharpen flavors.

Step-by-Step Instructions

Reduce the Guinness. Pour the 11.2 to 12 ounce bottle of Guinness into a small saucepan, bring to a boil, then reduce heat and simmer until reduced to 2/3 cup. This concentrates the stout flavor. Remove from heat and cool to room temperature before using. Tip: watch carefully as it reduces so it does not burn.
Preheat and prepare the pan. Preheat your oven to 350°F (175°C). Grease a 9-inch square baking pan so the brownies release easily after baking.
Melt butter and chocolate. In a microwave-safe bowl, combine 3/4 cup unsalted butter and 8 ounces coarsely chopped semi-sweet chocolate. Melt in short bursts, stirring between intervals, until smooth and fully combined. You can melt gently over a double boiler if you prefer.
Whisk in sugar and reduced Guinness. Stir the granulated sugar into the melted chocolate mixture, then whisk in the cooled, reduced Guinness until combined.
Add eggs and vanilla. Add the 3 large room temperature eggs and 1 teaspoon pure vanilla extract, whisking until the batter is glossy and uniform.
Fold in dry ingredients. Add 1 cup all-purpose flour, 1/2 teaspoon salt, and 1/2 teaspoon espresso powder if using. Whisk or fold until shiny and just combined. Do not overmix to keep the brownies tender.
Bake the brownies. Pour the batter into the prepared 9-inch square pan and bake in the preheated 350°F oven for 32 minutes. Check doneness with a toothpick inserted near the center; it should come out with a few moist crumbs but not wet batter.
Cool completely. Remove from the oven and allow the brownies to cool completely in the pan on a wire rack. Cooling fully makes frosting easier and cleaner to spread.
Make the frosting. In a mixing bowl, beat 1/2 cup softened unsalted butter until smooth, then gradually add 2 cups confectioners’ sugar and continue beating. Add 2 to 3 tablespoons of the reduced Guinness, 1 teaspoon espresso powder for frosting, 1/2 teaspoon pure vanilla extract for frosting, and 1/4 teaspoon salt for frosting. Beat until smooth and spreadable. Tip: add Guinness a little at a time to reach desired consistency.
Frost and cut. Spread the frosting evenly over the cooled brownies. Once set, cut into squares and serve. Store in an airtight container at room temperature for up to 1 week.

Recipe Details

Prep Time: 25 minutes
This includes reducing the Guinness and assembling the batter.
Cook Time: 32 minutes
Total Time: 57 minutes
Servings: 16 squares
Calories: Approximately 365 kcal per serving

Tips, Storage and Variations

Tips
- Use room temperature eggs to help the batter emulsify and become glossy.
- Cool brownies completely before frosting to prevent the frosting from melting.
- If the reduced Guinness cools and thickens, gently warm a tablespoon before adding to the frosting so it mixes smoothly.
Storage
- Store frosted brownies in an airtight container at room temperature for up to 1 week.
- For short term refrigeration, keep in an airtight container for up to 10 days, but allow to come to room temperature before serving for best texture.
Freezing
- Freeze unfrosted brownies tightly wrapped for up to 3 months. Thaw in the refrigerator or at room temperature, then frost.
- For frosted brownies, freeze individual squares on a tray until firm, then wrap each piece in plastic and store in an airtight container for up to 2 months.
Flavor variations using only the ingredients provided
- Make the espresso flavor more pronounced by using the optional 1/2 teaspoon espresso powder in the batter and the 1 teaspoon in the frosting for a stronger coffee-chocolate profile.
- For a slightly less sweet frosting, use 2 tablespoons of reduced Guinness instead of 3, which will thin the frosting while keeping the stout character.
- If you prefer a richer chocolate experience, use a bit less sugar in the batter, but do not change amounts without testing, as texture will be affected.

FAQ

How do I reduce Guinness for the recipe?
Bring the beer to a boil in a saucepan, then simmer until reduced to 2/3 cup, stirring occasionally. Cool before using.
Can I skip the espresso powder?
Yes. The espresso powder is optional and only used to intensify chocolate flavor.
How can I tell when the brownies are done?
A toothpick inserted near the center should come out with a few moist crumbs but not wet batter.
Can I make these ahead of time?
Yes. Bake and frost the brownies, then store in an airtight container at room temperature for up to 1 week.
What size pan do I need?
Use a 9-inch square baking pan as directed to ensure correct thickness and baking time.
Can I use a different stout?
You can, but flavor will vary. Stick to similar-strength stouts for best results.

Conclusion

These Guinness Brownies with Frosting are a decadent way to showcase stout in a chocolate dessert, combining fudgy texture and rich flavor in every bite. If you enjoy testing classic recipes with a twist, this one is rewarding and reliably delicious; for a different take on Guinness brownies with a boozy frosting, see Guinness Brownies at Sally’s Baking Addiction, and for a creamier frosting idea, consider this interpretation of Guinness Chocolate Brownies with Baileys Cream Cheese Frosting. Please try the recipe, enjoy sharing it with friends, and leave a note about how you served yours for cozy, delicious inspiration.

Guinness Brownies with Frosting

Print Recipe

Warm, fudgy, and quietly boozy, these Guinness Brownies with Frosting bring deep malt and roasted notes into a rich chocolate treat, perfect for a chilly evening or a celebratory dessert.

Author: hannah-reed
Prep Time: 25 minutes
Cook Time: 32 minutes
Total Time: 57 minutes
Yield: 16 squares 1x
Category: Dessert
Method: Baking
Cuisine: American
Diet: Vegetarian

Ingredients

Scale

11.2–12-ounce bottle Guinness Draught Stout, reduced
3/4 cup unsalted butter for brownie base
8 ounces semi-sweet chocolate, coarsely chopped
1 and 1/4 cups granulated sugar
3 large eggs, at room temperature
1 teaspoon pure vanilla extract
1 cup all-purpose flour
1/2 teaspoon salt
1/2 teaspoon espresso powder (optional)
1/2 cup unsalted butter, softened for frosting
2 cups confectioners’ sugar
2–3 tablespoons reduced Guinness for frosting
1 teaspoon espresso powder for frosting
1/2 teaspoon pure vanilla extract for frosting
1/4 teaspoon salt for frosting

Instructions

Reduce the Guinness. Pour the Guinness into a small saucepan, bring to a boil, then reduce heat and simmer until reduced to 2/3 cup. Cool to room temperature before using.
Preheat your oven to 350°F (175°C) and grease a 9-inch square baking pan.
Melt butter and chocolate in a microwave-safe bowl until smooth and fully combined.
Whisk in the granulated sugar and cooled, reduced Guinness until combined.
Add eggs and vanilla, whisking until the batter is glossy.
Fold in flour, salt, and espresso powder if using. Do not overmix.
Bake the brownies in the prepared pan for 32 minutes. Check doneness with a toothpick.
Cool completely in the pan on a wire rack.
Make the frosting by beating softened butter and gradually adding confectioners’ sugar, followed by reduced Guinness, espresso powder, vanilla, and salt until smooth.
Frost the cooled brownies, cut into squares, and serve.