The base is a plain cocoa brownie, baked until set with moist crumbs and cooled completely in the pan.
The mousse is made without eggs. Half a cup of hot cream with a little bloomed gelatin melts six ounces of semisweet chocolate; once barely warm, a cup of softly whipped cream is folded in. It is spread over the brownies and chilled for at least two hours.
Three Checks for Two Layers
Temperature decides whether the mousse holds.
Brownie base
Completely cool to the touch.
Warm brownies melt the mousse.
Chocolate mixture
Barely warm before the whipped cream is folded in.
Too hot deflates the cream; too cold turns grainy.
After 2 hours chilled
Mousse is firm at the edges and holds a knife cut.
Only then does it slice cleanly.
How to Make It
Pan lined
Heat oven to 350°F and line an 8-inch square pan.
Brownie batter
Whisk the melted butter, sugar, eggs and vanilla, then fold in the cocoa, flour and salt.
Base baked
Bake 25 to 30 minutes until set with moist crumbs. Cool completely.
Chocolate base for the mousse
Bloom the gelatin in the cold water for 5 minutes. Warm 1/2 cup cream until steaming, stir in the gelatin, then pour over the chopped chocolate and stir smooth. Cool until barely warm.
Cream folded in
Whip the remaining 1 cup cream to soft peaks and fold into the chocolate mixture.
Spread and set
Spread the mousse over the cooled brownies and chill at least 2 hours until set.
Finished and cut
Finish with chocolate shavings and cut into 16 squares.
Ingredient Notes
- Semisweet chocolate
- Six ounces, chopped fine so the hot cream melts it evenly.
- Powdered gelatin
- One teaspoon bloomed in a tablespoon of cold water.
- Heavy cream
- A cup and a half: half a cup hot for the chocolate, a cup whipped.
Success Tips
- Test the chocolate mixture on your wrist; it should feel barely warm before the cream goes in.
- Fold with a wide spatula in as few strokes as possible.
- Cut with a hot, dry knife for a clean mousse edge.
Why This Recipe Works
- A fully cooled base stops the mousse melting on contact.
- Gelatin lets the mousse set firm enough to cut in squares.
- Folding the whipped cream into barely warm chocolate keeps it airy.
- Two hours of chilling gives a clean line between the layers.
Serving Ideas
Serve cold squares on small plates so the brownie base and the mousse show side by side.
Storage and Reheating
Refrigerate
Keep the brownies covered in the refrigerator until serving.
Frequently Asked Questions
Is there raw egg in the mousse?
No. The mousse is set with gelatin and is egg-free.
How long does the mousse take to set?
At least 2 hours in the refrigerator.
