Preheat oven to 350 degrees Fahrenheit and line two oven trays with baking paper.

Beat the egg whites with 2/3 cup sugar until stiff peaks form. Set aside.

Beat the egg yolks with the remaining sugar and vanilla sugar until slightly thickened. Add oil and coffee-flavored hot water.

Slowly add the flour and baking powder.

Fold in the egg whites.

Divide the batter evenly between the two trays (it will be a very thin layer). Bake for approximately 10 to 12 minutes, just until they are spongy (the cake “bounces” back up when pressed). Cool to room temperature.

In a pot, bring all ingredients to a boil, mixing frequently. Lower the flame and simmer for approximately three minutes, still mixing frequently.

Remove from heat and leave to cool slightly.

Spread half of the ganache over one cake, top with the second cake, then cover with the remaining ganache.

Freeze for at least two hours to harden.

Use a round cookie cutter to cut circles out of the cake (easiest when cake is semi-frozen).

To serve, top with coffee ice cream and a drizzle of melted chocolate. For added height, double the cake stack by putting two disks together (as featured in the picture).