Place an 8-in/20-cm cake round on a sheet pan and place an 8-in/20-cm cake ring on top.
Slice the sponge cake into three even layers between ¼ and ½ in/0.6 cm and 1 cm thick.
Place the layer cut from the bottom of the cake into the bottom of the cake ring with the cut side up and moisten it with simple syrup. Ladle 8 oz/230 g of the Bavarian cream on