Make a batch of decadent Guinness Brownies for St. Patrick’s Day! These fudgy, chocolate brownies are made with reduced Guinness Stout, cocoa powder, and baking chocolate for a rich and moist texture. Take them up a notch with homemade Bailey’s frosting for an extra layer of flavor.

We love a good brownie recipe, and we especially love brownies covered in a layer of rich frosting. For St. Patrick’s Day I decided to pair two of my favorite recipes, Homemade Brownies and Coca-Cola Cake, and make a batch of Guinness Brownies with Bailey’s Frosting.

I added reduced Guinness stout beer to the homemade brownies and turned the chocolate frosting from the cake into Bailey’s frosting. Add the two together and you have an amazingly decadent batch of brownies.

Ingredients You’ll Need:

For the Brownies:

Guinness Extra Stout Beer: Guinness pairs well with chocolate and tones down the sweetness. Substitute it with other dark beers like porter or another brand of stout.
Butter: We opt for unsalted butter. Salted butter works, too. Just make sure to omit the added salt in the ingredients.
Sugar: Granulated sugar works great for these brownies because it dissolves nicely and adds the perfect amount of sweetness. Cane sugar makes a good substitute. We haven’t tested this recipe with sugar substitutes.
Vanilla Extract: We prefer pure vanilla extract. Use imitation vanilla extract if that’s what you have on hand.
Eggs: Use room temperature large eggs. We haven’t tested the brownies with an egg substitute.
Flour: We use all-purpose flour and have not made these brownies with another type of flour.
Cocoa Powder: Use unsweetened cocoa powder. Hershey’s Cocoa Powder was in our pantry, so that’s what I used. Off-brand would also work.
Salt: Just a pinch of kosher salt works. Omit if you use salted butter.
Espresso Powder: I ordered instant espresso powder on Amazon. Some supermarkets carry a similar product in the baking aisle or coffee area. This is optional but enhances the chocolate flavor.
Baking Chocolate: You’ll need 8 ounces of baking chocolate. We use semi-sweet chocolate but there are other varieties like German chocolate, milk chocolate, and dark chocolate among others. Choose your favorite.

For the Frosting:

Butter: Unsalted butter is our pick.
Bailey’s Irish Cream Liqueur: We keep a small bottle of Bailey’s in the fridge for coffee drinks, so that’s what I used in the frosting. Off-brand Irish cream liqueur works well, too.
Powdered Sugar: Any brand works.

How to Make Guinness Brownies with Bailey’s Frosting:

Scroll to the recipe card below for ingredient amounts and full instructions.

Reduce the Guinness:

In a saucepan, bring the Guinness to a boil then reduce it to a simmer. Allow the beer to simmer until reduced to about ⅓ cup, normally takes about 25 to 30 minutes. Let it cool for 10 to 15 minutes before making the brownie batter.

To Make the Brownies:

Preheat the oven to 350°F, and an 8×8-inch baking dish with parchment paper. Set aside.
Place the butter in a medium saucepan, and melt over very low heat. Add the sugar, vanilla, and eggs. Whisk to combine.
Pour in the Guinness reduction and stir until mixed.

Irish stout poured over eggs and sugar mixture.

Sift the flour, cocoa powder, salt, and espresso powder over the pan, and whisk until just combined. Don’t overmix; otherwise, the brownies will be dense and tough.
Adjust the heat to low-medium. Stir in the baker’s chocolate, and mix until melted. Transfer the batter to the prepared baking dish. Bake for 35 to 45 minutes or until a toothpick inserted in the center comes out clean or with a couple of crumbs.
Remove from the oven, and allow the brownies to cool for a few minutes before frosting.

Flour, cocoa powder, and salt sifted into a pan.

Chopped chocolate over melted chocolate mixture.

To Make Bailey’s Frosting:

In a large saucepan, whisk together the butter and Bailey’s until the butter melts.
Remove from heat, and whisk in the powdered sugar. Pour the warm frosting over the brownies and spread it into an even layer. Enjoy!

Tips for Success:

These brownies are a delicious treat to make for any occasion! Here are some tips to help you create the perfect batch:

Be sure to reduce the Guinness before adding it to the brownie batter.
If you choose a 9×9-inch pan, start checking the brownies a few minutes earlier. The thickness of the brownies will be slightly less than it would if using an 8×8-inch. Don’t forget to use a toothpick to check the doneness.
Glass baking pans are great; however, you’ll want to adjust the oven temperature and cook time. For glass pans, I recommend reducing the temperature to 325°F and increasing the cooking time to 45 to 55 minutes. Otherwise, the outsides of the brownies will overcook by the time the center is done.
Use a tall pan to boil and reduce the beer. Watch it closely because it easily boils over and makes a mess!
Avoid using chocolate chips in this recipe. They cause the brownies to harden as they set up.
To ensure that you get the most delicious, moist brownies, be sure to not overbake them (a few crumbs are okay)!
Adjust the baking time to your oven. Some ovens may take more time while others take less. Adjust accordingly.

Storage:

Refrigerator: Store leftovers in the refrigerator for up to 5 days.

Freeze: Individual brownies freeze well wrapped in plastic wrap and foil. Thaw in the fridge or at room temperature before serving.

Reheating: Brownies are best served slightly warm. Reheat on half power in the microwave just until barely warm. Take care not to overheat and melt the frosting.

What Is Guinness?

Guinness is a dark Irish dry stout brewed in Dublin, Ireland. It has an alcohol by volume (ABV) of 4.2 to 5%, with its signature roasted barley flavor. Guinness is known for its iconic creamy head (foam) and is one of the most popular beers worldwide.

Do Guinness Brownies Taste Like Beer?

No, they do not taste like beer. They have a strong chocolate flavor balanced out by the sweetness of the sugar. The frosting gives them a creamy sweetness with the flavor of Irish cream liqueur.

Can You Use a Different Type of Frosting?

The Bailey’s frosting may contain some alcohol even after being combined with the butter and powdered sugar. Replace the Bailey’s frosting with your favorite chocolate or vanilla frosting if desired.

What Are the Texture of These Brownies?

The edges of these Guinness brownies are fudgy but slightly more cake-like than the center. The center brownie(s) is like eating a piece of rich chocolate fudge. Softer than the outer edges and silky smooth.

Other Chocolate Desserts to Try:

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