These Bailey’s Chocolate Mousse Brownies are pure indulgence: a fudgy brownie base topped with a light Bailey’s mousse and finished with a silky chocolate ganache. Rich, decadent, and surprisingly easy to make, they’re a perfect treat for celebrating or sharing.
I did something delightfully indulgent—I combined Bailey’s and chocolate mousse on top of a dense fudge brownie. It was a deliciously guilty decision, and I’m fully owning it. The good news is I’m sharing the complete recipe so you can make them too.
With St. Patrick’s Day approaching, I wanted a recipe that highlights Bailey’s. Even if you don’t go all out for March 17, these brownies are a great excuse to celebrate something sweet. The components are straightforward and come together into a showstopping dessert.
These Bailey’s Chocolate Mousse Brownies are made of a few layers, but each step is simple. Here’s how they break down:
The Brownies
The brownie layer uses classic ingredients: melted butter, granulated sugar, vanilla, eggs, cocoa powder, flour, salt, and an optional pinch of instant espresso powder. I prefer a quality cocoa—Ghirardelli or another premium brand—to give the brownies a deep chocolate flavor. The instant espresso powder doesn’t make the brownies taste like coffee; it simply intensifies and enriches the chocolate notes for a more complex, fudgy result.
The Bailey’s Mousse
The mousse is a semi-homemade shortcut that’s both quick and reliable. A small amount of miniature marshmallows melts with chopped semi-sweet chocolate and some Bailey’s to create a chocolate base. Once that cools, you whip heavy cream with a bit more Bailey’s until stiff peaks form, then gently fold the whipped cream into the cooled chocolate mixture. The marshmallows give the mousse a light, springy texture without complicated tempering or gelatin.
The Ganache
The ganache is the finishing touch: warm heavy cream poured over semi-sweet chocolate chips, stirred until glossy and smooth. Drizzle or pipe the ganache over the set mousse for a shiny, rich topping that complements both the brownie and the airy mousse.
Combined, these layers deliver a fudgy brownie, a light yet boozy Bailey’s mousse, and a creamy ganache—each component enhances the others for a balanced, indulgent dessert.
These Bailey’s Chocolate Mousse Brownies are hard to beat when you want an impressive, delicious treat.
Bailey’s Chocolate Mousse Brownies
2 hrs
25 mins
2 hrs 25 mins
Ingredients
For the Brownies:
- 3/4 cup (1½ sticks) unsalted butter melted
- 1½ cups granulated white sugar
- 1 tsp vanilla extract
- 2 large eggs
- 1/2 cup cocoa powder
- 1/2 tsp salt
- 3/4 cup all-purpose flour
- 1/2 tsp instant espresso powder optional but recommended
For the Bailey’s Mousse:
- 3/4 cup miniature marshmallows
- 4 oz (1 bar) semi-sweet chocolate roughly chopped
- 1/4 cup + 2 Tbsp Bailey’s Irish Cream divided
- 1 cup heavy whipping cream
For the Ganache:
- 1/2 cup semi-sweet chocolate chips
- 1/4 cup heavy whipping cream
Instructions
- Preheat oven to 350°F. Line a 9×9″ light metal square baking pan with foil, allowing the foil to overhang the edges. Spray the foil with cooking spray and set the pan aside.
- In a medium bowl, whisk together the melted butter and granulated sugar. Add the vanilla and eggs, one at a time, whisking well after each addition. Stir in the cocoa powder, salt, flour, and instant espresso powder (if using) until a smooth, soft batter forms. Spread the batter evenly in the prepared pan.
- Bake for 22–25 minutes, or until a toothpick inserted near the center comes out with moist but not wet crumbs. Allow the brownies to cool completely in the pan.
- For the mousse: in a small saucepan over low heat, combine the miniature marshmallows, chopped chocolate, and 1/4 cup Bailey’s. Stir constantly until melted and smooth. Remove from heat and let the mixture cool for about 10 minutes.
- Whip the heavy cream with the remaining 2 tablespoons of Bailey’s on high speed until stiff peaks form, about 5–7 minutes. Gently fold the cooled chocolate-marshmallow mixture into the whipped cream until no streaks remain. Spread the mousse evenly over the cooled brownies. Cover and refrigerate at least 2 hours to set.
- Just before serving, make the ganache: heat the 1/4 cup heavy cream until hot (microwave ~30 seconds or warm on the stove), pour over the chocolate chips, let sit 3–5 minutes, then whisk until smooth and glossy. Drizzle the ganache over the set mousse, slice into squares, and serve. Store leftovers covered in the refrigerator to keep the mousse moist.
Notes
Use good-quality cocoa and chocolate for the best results—chocolate is the star of these brownies.
Some Bailey’s is cooked in the mousse base and more is folded into the whipped cream. Use discretion when serving to those who should not consume alcohol.
These supremely fudgy brownies are a crowd-pleaser and a delicious way to enjoy Bailey’s in dessert form.
Have a super sweet day!
xo, Hayley