Place one layer of the cake on your serving plate and wrap a strip of acetate (i.e., flexible food grade plastic) around the edge of the cake. Secure the edge of the acetate with a piece of tape.
Cut approximately 12 strawberries in half and arrange them with the cut side placed directly against the acetate. Try to make them all approximately the same height.
Pipe a layer of mousseline cream onto the cake and use the piping bag to fill in the gaps between the strawberries. Use an offset spatula or the back of a spoon to quickly smooth the cream. Then, add extra fruit to the middle of the cake (i.e., inside of the strawberry ring). I used raspberries, blackberries, blueberries, and quartered strawberries. When adding the fruit, do not let the fruit extend above the tops of the cut strawberries, otherwise, the second cake layer will not sit flat. Pipe the remaining mousseline cream. I like to use a piping bag because it allows for more control, however, feel free to spoon the cream in if you would prefer. Smooth the mousseline using an offset spatula or the back of a spoon.
Next, take the second layer of cake and place it gently on top of the mousseline cream. Try to drop it as evenly as possible so the cream doesn’t get pushed up one side of the cake. The goal with this dessert is to have clean layers without bleeding between layers. Take care with each component to achieve a beautiful finished product.
Pipe a layer of Chantilly cream over the top of the cake and smooth using an offset spatula or the back of a spoon. You can leave it flat or use a piping bag to add Chantilly cream decorations to the top of the cake.
At this point, place in the fridge (uncovered) for at least 2 hours for the mousseline to set. If you want to ensure the fruit juices don’t bleed onto the whipped cream, wait until just before serving and then add the “decoration” fruit.