Perfect for St. Patrick’s Day these chocolate Guinness brownies are moist and tasty with extra flavor from the booze. They are topped off with a thick layer of chocolate ganache flavored with more Guinness. Made with a boxed brownie mix as a base these are a simple and delicious dessert.

It is March, which means St. Patrick’s Day is almost here. And nothing says St. Patrick’s Day like cooking with booze!
I like to use the distinctive flavor of Guinness Stout in my cooking, whether it is making Guinness Chocolate Chip cookies or using the Guinness to create a tasty broth in my Instant Pot lamb stew. These Guinness brownies are an easy Irish inspired boozy dessert.
What is Guinness?
Guinness is a dark Irish stout that has been made in Ireland for hundreds of years. It has a distinctive taste with a mixture of malty sweetness and a hint of bitterness and coffee flavor.
Why Use Guinness in Baking?
Guinness Stout pairs extremely well with chocolate. It intensifies the flavor of the chocolate and adds a little bit of malt taste to the dessert.
I am not a big fan of most beer and wouldn’t actually want to drink an entire bottle of Guinness. I am more of a wine drinker than a beer drinker.
But using Guinness in baking is another matter entirely. The flavor goes amazingly well with chocolate without giving it an overwhelming beer flavor.
So even if you aren’t a big fan of Guinness or beer, don’t assume you won’t enjoy these brownies! These brownies are moist and fudgy with a delicious flavor.
How to Make Guinness Brownies
This is a very simple recipe because it uses a boxed brownie mix as the base. This simplifies the baking and means dessert can be ready quickly.
I used a box of Fudge Brownie mix. I used the amount of oil directed on the package and replaced the water with an equal amount of Guinness.
I also used one less egg than the directions called for to make the brownies more fudgy and less cake-like. That is personal preference, my family and I prefer fudge like brownies.
Simply mix the ingredients together and bake as directed by the box. Then let the brownies cool completely before cutting or adding a ganache topping.
I chose to make these brownies in a 13 x 9 baking pan. This results in thin and fudgy brownies. If you prefer thicker brownies you can bake the brownies in a 9 x 9 square pan. This will give you thicker brownies with a thicker layer of ganache on top.
How to Make the Guinness Chocolate Ganache
The brownies taste good as is, but they taste even better with a thick layer of Guinness flavored Chocolate Ganache on top!
I used semi-sweet chocolate chips to make the ganache. Combine the chocolate chips with butter and Guinness, and microwave for 30 seconds.
Then take the mixture out, stir it and microwave it for another 30 seconds. Continue this, stirring every 30 seconds until the butter and chocolate chips start to melt.
Then stir the chocolate mixture until it is smooth. Finally stir in some powdered sugar and stir until it is smooth and creamy.
Pour the ganache over top of the brownies and spread it out evenly. The ganache will harden into a nice layer of rich chocolatey goodness.
Substitutes for Guinness
Guinness is basically the key ingredient in this recipe. If you prefer to avoid alcohol, Guinness makes a non-alcoholic version of their stout. That way you can have the distinctive Guinness flavor without the alcohol. You could also substitute another dark stout in its place.
Find More Boozy Desserts
If you love boozy desserts, try this Tiramisu Trifle recipe, Limoncello Pound Cake recipe, or Mini Rum Cake recipe!
Guinness Brownies with Chocolate Ganache
Ingredients
Brownies
- 1 box fudge brownie mix
- 1/4 cup Guinness Stout
- 1/2 cup oil
- 1 egg
Ganache
- 10 ounces semi sweet chocolate chips
- 4 Tablespoons butter
- 4 Tablespoons Guinness Stout
- 1/2 cup powdered sugar
Instructions
- Spray a 13 x 9 inch baking pan with cooking spray. Preheat the oven to 350 F.
- Put the brownie mix in a bowl and add the Guinness, oil and egg. Stir until well blended.1 box fudge brownie mix, 1/4 cup Guinness Stout, 1/2 cup oil, 1 egg
- Pour into the prepared pan and spread out evenly. Bake for 24-30 minutes, until a toothpick inserted into the brownies comes out almost clean.
- Let brownies cook in pan.
- When they are cool put the chocolate chips, butter and Guinness in a microwavable bowl.10 ounces semi sweet chocolate chips, 4 Tablespoons Guinness Stout, 4 Tablespoons butter
- Microwave for 30 seconds and then remove and stir. Repeat, stirring every 30 seconds until the chocolate chips and butter start to melt.
- Stir until the chocolate chips are completely melted and smooth. Add the powdered sugar and stir again until smooth.1/2 cup powdered sugar
- Pour the ganache over top of the cooled brownies and spread out to the edges. Let cool and cut into squares.
Notes
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Nutrition Information
Nutrition facts are estimates.