Glossy Chocolate Mousse Cake with Mirror Glaze

Using clean, dry beaters, whip the chilled egg white on high speed until foamy and white. Add the granulated sugar in 4 additions, beating well after each addition, until the meringue forms soft peaks with tips that gently droop.

Fold the meringue into the almond batter in 3 additions. Add the next portion while the batter still looks slightly marbled, then continue folding until no streaks of meringue remain. Fold about 10 more times to make the batter smooth without deflating it too much.

Spread the batter evenly into the prepared paper mold. Reduce the oven temperature to 190°C / 374°F and bake for about 10 minutes, or until the sponge springs back lightly. Transfer to a rack and cool completely.

Trim the cooled sponge into a 20 x 7 cm rectangle, making it slightly smaller than the base of the half-round cylinder pan. Cover loosely with plastic wrap and set aside.

Make the chocolate mousse. Sprinkle 5 g powdered gelatin over 2 tbsp water and let it bloom. In a chilled bowl set over ice water, whip 200 g heavy cream until thickened and the whisk marks hold softly. Refrigerate until needed.

Place the chopped dark chocolate in a heatproof metal bowl. Bring a small pot of water to a boil, then turn off the heat. Set the bowl over the pot, making sure the bowl does not touch the hot water.

Let the chocolate sit for 30 seconds, then stir gently until fully melted and smooth. Remove the bowl from the pot and set aside.

Warm the milk and sweetened condensed milk in a small saucepan over medium-low heat for 1 to 2 minutes, stirring constantly. Remove from the heat, add the bloomed gelatin, and stir until completely dissolved. Cool the mixture to 43°C / 109°F or below, stirring occasionally.

Transfer the melted chocolate to a large bowl. Add the cooled milk mixture and stir until glossy and smooth. Let it cool to 35°C / 95°F or below before adding the cream.

Stir the whipped cream briefly to loosen it. Fold it into the chocolate mixture in 3 additions, adding the next portion while the mixture is still slightly marbled. Fold gently until the mousse is smooth and uniform.

Assemble the cake. Line the half-round cylinder pan with cake film. A light brush of kirsch, brandy, or water on the pan can help the film cling smoothly. Fill the pan with mousse, stopping about 1 cm below the rim, and level the surface.

Place the trimmed sponge on top of the mousse and press gently so the sponge sits level with the mousse. Freeze overnight until completely firm.

The next day, unmold the frozen mousse cake. Warm the outside of the pan with a hot towel, then carefully slide a knife between the cake film and pan if needed. Lift the cake out by the film and return it to the freezer while you prepare the glaze.

Make the mirror glaze. Sprinkle 6 g powdered gelatin over water and let it bloom. In a small saucepan, combine 90 g water, 75 g heavy cream, and 165 g granulated sugar. Bring to a boil, stirring occasionally, then remove from the heat and stir in the bloomed gelatin until dissolved.

Sift in the cocoa powder and whisk until smooth. Transfer the glaze to a tall narrow container and blend with a hand blender for 1 to 2 minutes, keeping the blender head submerged to avoid adding too many bubbles.

Strain the glaze through a fine-mesh sieve. Cool it over an ice bath, stirring occasionally, until it reaches 25°C / 77°F or slightly below and thickens enough to coat the cake evenly.

Set the frozen mousse cake on a rack or a small overturned container placed over a tray. Pour the glaze over the cake in one steady motion so it covers the surface completely. Refrigerate for about 3 hours to thaw and set. Decorate with whipped cream, strawberries, and mint before serving.