Guinness Brownies with Frosting

These Guinness Brownies with Frosting are fudgy, deeply chocolatey squares with a subtle malty tang from reduced Guinness. The brownies bake up dense and shiny with a crackly top and moist, chewy center, while the smooth frosting adds a creamy, stout-scented finish. You will notice warm cocoa aroma mixed with a whisper of coffee-like bitterness if you use the optional espresso powder. This recipe is ideal for cozy gatherings, St. Patrick’s Day treats, or whenever you want a grown-up brownie that balances sweet and bitter. Serve them at room temperature for the best texture, or chill briefly if you prefer firmer slices. If you enjoy creative brownie spins, you might also like a twist on toppings like these brownies topped with pecan pie for a nutty contrast.

Ingredients

11.2–12-ounce bottle Guinness Draught Stout beer, reduced to concentrate the malt flavor and add depth to the batter and frosting.
3/4 cup unsalted butter, for rich fat and tender crumb in the brownie base.
8 ounces semi-sweet chocolate, coarsely chopped, gives the primary chocolate flavor and glossy texture when melted with butter.
1 and 1/4 cups granulated sugar, for sweetness and structure in the brownies.
3 large eggs, at room temperature, help bind the batter and create a shiny top.
1 teaspoon pure vanilla extract, enhances the chocolate and balances the stout.
1 cup all-purpose flour, provides structure; do not overmix to keep brownies tender.
1/2 teaspoon salt, rounds out flavor and balances sweetness.
1/2 teaspoon espresso powder (optional), amplifies chocolate intensity without adding liquid.
1/2 cup unsalted butter, softened to room temperature, base for the frosting, whipped light and smooth.
2 cups confectioners’ sugar, for a silky, spreadable frosting sweetness.
2–3 tablespoons reduced Guinness, used in the frosting for a subtle stout flavor and to thin the frosting as needed.
1 teaspoon espresso powder, folded into the frosting for depth and a hint of mocha.
1/2 teaspoon pure vanilla extract, brings warmth and complexity to the frosting.
1/4 teaspoon salt, balances the frosting sweetness for a rounded finish.

For another frosting-focused treat, see these pecan pie cupcakes with brown sugar frosting for inspiration.

Step-by-Step Instructions

Reduce the Guinness. In a small saucepan, bring the Guinness to a boil over medium-high heat. Reduce to medium heat and simmer until reduced down to 2/3 cup, about 12 to 15 minutes. Cool for at least 10 minutes. Tip: watch closely as it reduces so it does not boil over.
Prepare the oven and pan. Preheat the oven to 350°F (175°C) and grease a 9-inch square baking pan. You can line the pan with parchment for easier removal.
Melt chocolate and butter. Melt the 3/4 cup unsalted butter and the 8 ounces coarsely chopped semi-sweet chocolate in a microwave-safe bowl in 30-second increments, whisking between bursts until smooth. Work carefully so the chocolate does not seize.
Combine sugar and Guinness. Whisk in the 1 and 1/4 cups granulated sugar and 1/2 cup of the reduced Guinness until combined. Then whisk in the 3 large eggs and 1 teaspoon pure vanilla extract until the mixture is glossy.
Add dry ingredients. Add the 1 cup all-purpose flour, 1/2 teaspoon salt, and 1/2 teaspoon espresso powder if using. Whisk until the batter is thick and shiny. Do not overmix once the flour is incorporated.
Bake the brownies. Pour the batter into the prepared pan and bake for 32 minutes. Test with a toothpick inserted into the center; it should come out with a few moist crumbs, not wet batter.
Cool completely. Allow the brownies to cool completely in the pan before frosting. Cooling fully prevents the frosting from sliding.
Make the frosting. To make the frosting, beat the 1/2 cup softened unsalted butter until smooth, then gradually add the 2 cups confectioners’ sugar. Mix in 2 to 3 tablespoons reduced Guinness, 1 teaspoon espresso powder, 1/2 teaspoon pure vanilla extract, and 1/4 teaspoon salt until smooth. Adjust thickness with additional reduced Guinness a teaspoon at a time if necessary. Tip: if the frosting is too thin, add a little more confectioners’ sugar and beat until thick.
Frost and cut. Frost the cooled brownies with an offset spatula and cut them into squares once the frosting is set.
Store properly. Store the brownies covered at room temperature for up to 1 week.

For a different rolling and presentation technique, check out this pumpkin roll with caramel praline frosting for frosting ideas you can adapt.

Recipe Details

Prep Time: 25 minutes (includes Guinness reduction and cooling)
Cook Time: 32 minutes
Total Time: 57 minutes
Servings: about 16 squares
Calories: approximately 370 calories per serving

Tips, Storage & Variations

Tips: Use room temperature eggs to help the batter emulsify for a shiny top. When melting chocolate, use gentle heat and stir frequently. If you use the optional espresso powder, dissolve it first in a teaspoon of warm reduced Guinness for even distribution.
Storage: Keep brownies in an airtight container at room temperature for up to 1 week. If your kitchen is warm, store them in the refrigerator and bring to room temperature before serving for the best texture.
Freezing: You can freeze unfrosted brownies for up to 3 months. Wrap tightly in plastic wrap and then foil. Thaw in the refrigerator overnight, then frost. For frosted brownies, flash freeze on a tray, then wrap and store for up to 2 months.
Flavor variations using existing ingredients only: Increase the espresso powder in the batter and frosting for a mocha-forward brownie, or use the full reduced Guinness amount in the frosting for a stronger stout note. For a lighter frosting, reduce the confectioners’ sugar slightly and add an extra tablespoon of reduced Guinness until you reach the desired spreadability. For inspiration pairing chocolate with warm spices, you can adapt techniques from soft pumpkin cookies with cinnamon frosting to layer textures.

FAQ

Q: Do I need to boil the Guinness before adding it to the batter?
A: Yes, reducing the Guinness concentrates its flavor and removes some water so the batter has the right texture.

Conclusion

These Guinness Brownies with Frosting are a decadent way to bring deep chocolate and stout flavor to your dessert table. They are straightforward to make and store well, which makes them ideal for sharing with friends and family. For more recipes and variations that play with stout and chocolate flavors, explore Guinness Brownies – Sally’s Baking Addiction and this creative take on chocolate brownies with a creamy topping at Guinness Chocolate Brownies Baileys Frosting. Enjoy baking these fudgy squares and feel free to share your results with others for a cozy, delicious treat.