Place an 8-in/20-cm cardboard cake round on a sheet pan and place an 8-in/20-cm cake ring on top. Slice the vanilla sponge into two even layers between ¼ and ½ in/0.6 cm and 1 cm thick, place one layer into the cake ring, and moisten with simple syrup.
Moisten the chocolate roulade sheet with the simple syrup. Combine 12 oz/340 g of the heavy cream with the con