These chocolate mousse brownies are rich, fudgy, and topped with a silky mousse layer—an elegant, make-ahead dessert that’s always a crowd-pleaser.

Brownie Layer:

All-purpose flour

Cocoa powder (Dutch-processed preferred)

Unsalted butter, melted

Granulated sugar

Eggs

Vanilla extract

Salt

Optional: cornstarch or baking powder

Mousse Layer:

Semi-sweet chocolate (chips or chopped bar)

Heavy whipping cream

Optional: marshmallows

Optional: gelatin (for firmer mousse)

Optional Garnish:

Chocolate curls or shavings

Cocoa powder dusting

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Brownie Base:

Preheat oven to 350 °F (175 °C). Line a 9×13″ or 9″ square pan with parchment.

Mix flour, cocoa, salt (and baking powder or cornstarch if using).

In another bowl, mix melted butter and sugar. Beat in eggs and vanilla.

Fold in dry ingredients until just combined.

Spread batter in the pan and bake 25–35 minutes until edges are set. Cool completely.

Mousse Layer:

Gently melt chocolate with a portion of the cream (or marshmallow mix), then cool slightly.

Whip the remaining cream to soft or stiff peaks.

Fold the whipped cream into cooled chocolate until smooth. Optionally stir in bloomed gelatin for stability.

Assemble & Chill:

Spread mousse over the cooled brownie layer.

Garnish with chocolate shavings or cocoa powder if desired.

Chill for at least 2 hours, or overnight, before slicing.

Marshmallows create a fluffier mousse alternative.

For firmer slices, add a small amount of gelatin.

Mini brownie versions are great for parties—adjust baking time accordingly.