Savor this exquisite cake at La Poularde in Houdan, where it's a true delight.
Preparation spans two days: start with the biscuit and chocolate mousse on day one, then whip up coffee Chantilly cream, assemble, and optionally ice on day two.
Timings: Biscuit: 20 mins prep, 15 mins bake. Mousse: 20 mins. Chantilly: a few minutes. Assembly: 30-35 mins.
Serves 8-10 people.
Chocolate Biscuit: 4 whole eggs, 100g caster sugar, 60g flour, 15g cocoa powder.
Chocolate Mousse: 125g dark chocolate, 2 egg yolks, 75g softened butter, 4 egg whites, 75g caster sugar, 15g melted dark chocolate.
Coffee Whipped Cream: 1/4L whipping cream, 1 tbsp instant coffee powder, 1 sheet gelatin, 1 dl rum-flavored sugar syrup.
Frosting: 100g dark chocolate, a little water.
- Biscuit: Preheat oven to 175°C (position 3). Line a 25x30cm rimmed baking sheet (2cm high) with buttered, floured parchment. Sift flour and cocoa together; set aside. Beat eggs and sugar at medium speed until thick and firm. Fold in flour-cocoa mix vigorously. Spread dough 15mm thick on parchment. Bake 15 mins. Unmold onto a tea towel over a wire rack; cool at room temp.
- Mousse: Melt 125g chocolate in bain-marie until smooth; off heat, beat in softened butter, then yolks one by one for a thick mayonnaise texture. Separately, melt 15g chocolate. Whip whites to froth, add sugar gradually until firm and glossy; incorporate melted chocolate. Fold whites into chocolate mix for smooth mousse. Chill in terrine.
- Coffee Chantilly: Soften gelatin in cold water, then melt. Whip cream with coffee at medium speed; add gelatin. Stop at light peaks. Prepare light rum-flavored sugar syrup.
- Assembly: Cut biscuit into 3 equal strips. Fill two 15mm piping bags: one mousse, one Chantilly. Place first strip on board; brush with syrup. Pipe 3 even mousse lines lengthwise; fill gaps with Chantilly. Top with second strip, syrup, then invert fillings (Chantilly lines, mousse fill). Add third strip; press gently. Smooth edges; chill 1+ hour until very cold. Slice with hot-water-dipped knife.
Frosting: Melt chocolate with a little water until smooth. Pour over cold top layer; spread briskly with spatula.
Adapted from Martine Jolly's "Le Chocolat: A Devouring Passion" (Robert Laffont), a trusted source for chocolate artistry.
