Guinness Brownies with Guinness Frosting

These Guinness Brownies with Guinness Frosting are a decadent, slightly boozy twist on classic fudgy brownies. The stout reduces into a syrupy concentrate that deepens the chocolate flavor and keeps the crumb moist, while the frosting echoes that roasted malt note for a grown up, balanced finish. Expect a dense, fudgy interior with a shiny crackled top and a creamy, lightly boozy frosting that melts on the tongue. The aroma opens with dark chocolate and roasted coffee notes, followed by a warm caramelized scent from the reduced beer. These brownies are ideal for cozy nights, holiday dessert tables, or any occasion where you want a showstopper that still feels homey. If you enjoy pairing unexpected flavors in comforting recipes, you might also enjoy this Easy Homemade Spaghetti Os with Meatballs for a nostalgic weeknight meal.

Ingredients

1 (11.2–12-ounce) bottle Guinness Draught Stout beer — reduced for concentrated flavor and moisture.
(Use the full bottle to reduce down to the specified amount.)
3/4 cup unsalted butter — for a rich, tender brownie base.
2 (4-ounce) bars semi-sweet chocolate, coarsely chopped — provides the chocolate backbone and fudgy texture.
1 and 1/4 cups granulated sugar — balances bitterness and helps create a shiny top.
3 large eggs, at room temperature — add structure and richness; room temperature helps emulsify the batter.
1 teaspoon pure vanilla extract — enhances chocolate flavor.
1 cup all-purpose flour — provides structure without making the brownies cakey.
1/2 teaspoon salt — balances sweetness and enhances flavor.
1/2 teaspoon espresso powder (optional) — intensifies the chocolate and Guinness notes.
1/2 cup unsalted butter, softened to room temperature (for frosting) — makes the frosting smooth and creamy.
2 cups confectioners’ sugar — sweetens and thickens the frosting for spreadability.
2–3 tablespoons reduced Guinness (for frosting) — adds that same stout character to the frosting; start with 2 tablespoons.
1 teaspoon espresso powder (for frosting) — adds depth and a subtle coffee note.
1/2 teaspoon pure vanilla extract (for frosting) — rounds the frosting flavor.
1/4 teaspoon salt (for frosting) — balances the sweetness.

(For more simple weeknight ideas, see this Easy Homemade Spaghetti Os with Meatballs.)

Step-by-step Instructions

Reduce the Guinness. In a small saucepan, bring the Guinness to a boil over medium-high heat. Reduce the heat to medium and let it simmer until it reduces down to 2/3 cup, about 12 to 15 minutes. Set aside to cool for at least 10 minutes. Tip: watch closely toward the end so it does not burn.
Prepare the pan and oven. Preheat the oven to 350°F (175°C) and grease a 9-inch square baking pan so the brownies release cleanly.
Melt butter and chocolate. In a large microwave-safe bowl, combine the 3/4 cup butter and the chopped semi-sweet chocolate. Melt in 30-second increments, whisking after each until smooth.
Combine sugar and Guinness. Whisk in the granulated sugar and 1/2 cup of the reduced Guinness until fully combined and glossy.
Add eggs and vanilla. Add the eggs and vanilla extract, whisking until well incorporated and the batter looks smooth.
Add dry ingredients. Add the flour, salt, and the optional 1/2 teaspoon espresso powder. Whisk until just combined; do not overmix to keep the brownies fudgy.
Bake the brownies. Pour the batter into the prepared baking pan and bake for 32 to 35 minutes or until a toothpick inserted into the center comes out with a few moist crumbs. Tip: a few moist crumbs indicate fudgy brownies; if it comes out wet, bake a few minutes longer.
Cool completely. Let the brownies cool completely in the pan before frosting so the frosting does not melt.
Make the frosting. Beat the 1/2 cup softened butter until smooth. Gradually add the 2 cups confectioners’ sugar and mix until combined.
Finish the frosting. Beat in 2 tablespoons of the reduced Guinness, along with the 1 teaspoon espresso powder, 1/2 teaspoon vanilla extract, and 1/4 teaspoon salt. Adjust consistency with the third tablespoon of Guinness if you want a thinner spreadable frosting.
Frost and serve. Once cooled, frost the brownies with the prepared frosting and cut into squares. Store any leftovers at room temperature. Tip: for cleaner slices, chill briefly and use a warm knife.

(For another take on comforting classics, check this Easy Homemade Spaghetti Os with Meatballs.)

Recipe Details

Prep Time: 25 minutes
Cook Time: 35 minutes
Total Time: 1 hour
Servings: 16 squares
Calories: Approximately 370 kcal per serving

(See a simple weeknight recipe example at Easy Homemade Spaghetti Os with Meatballs.)

Tips, Storage & Variations

Tips:
- Use room temperature eggs for a smoother batter and even rise.
- When melting chocolate and butter, stir well between microwave intervals to prevent scorching.
- If you prefer a stronger beer note in the frosting, add the third tablespoon of reduced Guinness slowly until you reach the desired intensity.
Storage:
- Store frosted brownies at room temperature in an airtight container for up to 3 days.
- For longer storage, refrigerate up to 7 days. Bring to room temperature before serving for best texture.
Freezing:
- Freeze unfrosted brownies tightly wrapped for up to 3 months. Thaw, then frost.
- You can also freeze frosted brownies in a single layer on a baking sheet, then transfer to a freezer bag. Thaw in the refrigerator overnight.
Flavor variations using existing ingredients only:
- Espresso-forward: Add the optional 1/2 teaspoon espresso powder into the batter and keep the 1 teaspoon in the frosting for a pronounced mocha note.
- Extra chocolate texture: Reserve a few chopped bits of the semi-sweet chocolate and sprinkle on top before frosting to add bite and sheen.
- Stronger Guinness presence: Stir the final 1 tablespoon of reduced Guinness into the frosting for a more assertive beer note.

(For more inspiration on comforting meals, visit Easy Homemade Spaghetti Os with Meatballs.)

FAQ

Q: Can I use another stout instead of Guinness?
A: Yes, you can substitute a similar stout, but flavor will vary slightly. Use the same reduction method.

Q: Do I need to reduce the Guinness first?
A: Yes, reducing concentrates flavor and removes some alcohol, which prevents a watery batter.

Q: Can I make these dairy-free?
A: This recipe uses butter in batter and frosting, so dairy-free swaps would change texture and are not covered here.

Q: How do I know when brownies are done?
A: Insert a toothpick in the center; a few moist crumbs indicate fudgy brownies, not wet batter.

Q: Can I skip the espresso powder?
A: Yes, espresso powder is optional and only enhances the chocolate and stout notes.

Q: How long should I cool before frosting?
A: Cool completely in the pan, about 1 to 1.5 hours at room temperature, before frosting.

Conclusion

These Guinness Brownies with Guinness Frosting are a lovable mix of fudgy chocolate and roasted stout notes that feel special without being fussy. They are a great pick for gatherings, chilly evenings, or any time you want a rich dessert with a subtle adult twist. For another well-tested take on Guinness brownies, see Guinness Brownies with Guinness Frosting – WellPlated.com. If you want a different home baker perspective and techniques, try Guinness Brownies – Sally’s Baking Addiction. Give the recipe a try, share with friends, and enjoy that first warm, chocolatey bite.

Guinness Brownies with Guinness Frosting

Print Recipe

Decadent brownies with a slightly boozy twist from reduced Guinness, topped with a creamy frosting that echoes roasted malt notes.

Author: hannah-reed
Prep Time: 25 minutes
Cook Time: 35 minutes
Total Time: 60 minutes
Yield: 16 squares 1x
Category: Dessert
Method: Baking
Cuisine: American
Diet: Vegetarian

Ingredients

Scale

1 (11.2–12-ounce) bottle Guinness Draught Stout beer, reduced
3/4 cup unsalted butter
2 (4-ounce) bars 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: In a small saucepan, bring the Guinness to a boil over medium-high heat. Reduce the heat to medium and let it simmer until it reduces down to 2/3 cup, about 12 to 15 minutes. Set aside to cool for at least 10 minutes.
Prepare the pan and oven: Preheat the oven to 350°F (175°C) and grease a 9-inch square baking pan.
Melt butter and chocolate: In a large microwave-safe bowl, combine the 3/4 cup butter and the chopped semi-sweet chocolate. Melt in 30-second increments, whisking after each until smooth.
Combine sugar and Guinness: Whisk in the granulated sugar and 1/2 cup of the reduced Guinness until fully combined and glossy.
Add eggs and vanilla: Add the eggs and vanilla extract, whisking until well incorporated.
Add dry ingredients: Add the flour, salt, and optional espresso powder. Whisk until just combined.
Bake the brownies: Pour the batter into the prepared baking pan and bake for 32 to 35 minutes.
Cool completely: Let the brownies cool completely in the pan before frosting.
Make the frosting: Beat the 1/2 cup softened butter until smooth, then gradually add the confectioners’ sugar and mix until combined.
Finish the frosting: Beat in 2 tablespoons of the reduced Guinness, espresso powder, vanilla extract, and salt.
Frost and serve: Frost the cooled brownies and cut into squares.