Make the Sponge Cake

1. Preheat Oven: Preheat to 350°F (175°C). Line a 9-inch round cake pan with parchment paper.
2. Prepare Batter: In a large bowl, beat eggs and sugar until pale and fluffy. Gently fold in sifted flour and vanilla extract, taking care not to deflate the batter.
3. Bake: Pour into the prepared pan and bake for 20-25 minutes, or until a toothpick comes out clean. Let cool completely before slicing into two even layers.

Prepare the Coffee Syrup

1. Brew Espresso: Combine espresso, sugar, and coffee liqueur in a small saucepan over low heat. Stir until sugar dissolves, then let cool.
2. Brush Layers: Use a pastry brush to generously soak each sponge layer with the syrup.

Make the Mascarpone Mousse

1. Whip Cream: Beat heavy cream to soft peaks and set aside.
2. Prepare Mascarpone Mixture: Beat mascarpone, powdered sugar, and vanilla until smooth. Melt the bloomed gelatin and mix into the mascarpone.
3. Combine: Gently fold the whipped cream into the mascarpone mixture until fully combined.

Assemble the Entremet

1. Layer One: Place the first sponge layer in a cake ring. Spread half the mascarpone mousse evenly over the sponge.
2. Layer Two: Add the second sponge layer and brush with more coffee syrup. Spread the remaining mousse on top, smoothing the surface.
3. Chill: Refrigerate for at least 2 hours to set.

Prepare the Chocolate Glaze

1. Heat Cream: Bring heavy cream to a gentle simmer. Pour over chopped chocolate and stir until smooth.
2. Glaze Cake: Pour the glaze over the chilled entremet, letting it drip down the sides.

Optional: Prepare the Mirror Glaze

1. Cook Glaze: Combine water, sugar, and glucose syrup in a saucepan. Heat to 103°C (217°F).
2. Combine Ingredients: Remove from heat and stir in condensed milk, white chocolate, and bloomed gelatin until smooth. Let cool to 90°F (32°C) before pouring over the cake.

Decorate the Entremet

1. Dust with Cocoa: Use a fine sieve to dust the top with cocoa powder.
2. Add Garnishes: Decorate with chocolate curls, coffee beans, or gold leaf for a luxurious finish.