Cut out three 12-inch rings of the sponge cake.
Place one of the sponges in the ring and the two others to the side for now.
Spread out the raspberry jam on the first sponge, stay ½ inch from the edge of the sponge.
Add the second sponge on top of the raspberry jam.
Spread out the pastry cream as the second layer going all the way out to the ring.
Whip the heavy cream to a firm peak and add about 2 cups on top of the pastry cream forming a rounded top in the middle.
Add the last sponge on top of the cream making sure that it is forming a dome.
Remove the ring carefully and cover the whole cake in the left-over cream.
Cover the whole cake in plastic wrap and place in fridge to set for 2 hours. This will make it easier and more stable to cover with the marzipan.
Color your marzipan green leaving around 3 ½ tablespoons that will be for the rose later on.
Roll out the marzipan between two plastic sheets and cover the cake like you would do with any fondant cake. Just be aware that marzipan is not as elastic and forgiving as fondant and might need a couple of practice runs to make it look smooth. This is the tricky part and once it is on the cake it cannot be removed.
Color the last bit of marzipan pink and turn it into a rose.
Dust the cake with powdered sugar and place the rose on top in the middle