Gently toast the almonds in a dry pan until pale golden
Let them cool completely
Process the almonds and sugar until fine, add 1/3rd C of sugar, and process until very fine
Whisk the eggs, egg yolk, sour cream, vanilla, lemon oil in a medium bowl. Mix until just combined.
Transfer the almond and sugar mix to a standing mixer bowl, add the remaining sugar, flour, baking powder, baking soda, salt & lemon zest
Using the paddle attachment, stir for a few seconds and then add in the butter and mix until all the dry ingredients are moistened.
Mix at medium speed for another 30 seconds and then add the egg mixture in three batches, mixing completely between each batch.
Divide between two pre pepped 6 inch round pans.
Bake for 35 minutes or until the cake tester comes out clean.
While the cakes are baking, make the lemon syrup
Heat the sugar and lemon juice until it dissolves, keep the heat on medium and keep stirring.
Once the sugar is dissolved, remove from heat and let it cool.
Let it cool
Once the cakes are baked, remove from oven, place on a wire rack to cool and apply half the lemon syrup while they are still in their tins.
When the cakes cool, unmold and apply the rest of the syrup on the other side.
Color Marzipan and Make the Rose
Set aside a small amount of plain marzipan (about the size of a walnut) to make a rose for decoration. Knead the remaining marzipan on a surface dusted with icing sugar until it becomes softer and smooth (the warmth from your hands will help this).
Add a small amount of green food colouring and knead it into the marzipan to get the desired shade of green. You might need to add a little more green or yellow food colouring to get the right colour – anything from pastel green to bright spring green .
Wrap tightly in plastic and refrigerate until you are ready to cover the cake.
To make the rose
Tint the reserved plain marzipan with a tiny bit of red food coloring to make it pink. Then follow this video link
Assemble the cake
In a large bowl, whip the heavy cream until soft peaks form. Add sugar to taste (keep in mind that the rest of the cake components are sweet, so the whipped cream should be very lightly sweetened at most) and continue whipping the cream until stiff. You want it to be sturdy enough to provide structure to the cake, but not over-whipped enough to make butter. Set the whipped cream aside.
Divide the cakes into two uniform layers each. Keep one layer aside and work with three layers.
Place one of remaining layers on a cake board or serving platter and spread it evenly with the raspberry jam. Spread or pipe half the chilled custard over the jam in an even layer, leaving enough room around the edges so that it doesn't spill over the sides of the cake.
Top the custard with another layer of cake. Spread or pipe the remaining custard evenly over it, again leaving some room around the edges.
Reserve ½ cup of the stiffly whipped cream. Pile the rest into a mound on top of the custard. Spread it into a thick layer with a thin, flexible spatula or off-set spatula, then hold the spatula at an angle to shape the whipped cream into a dome, piling it up in the middle of the cake as much as possible.
Place the final layer of sponge cake on top of the whipped cream. Do not press on the top of the cake – instead, gently tuck the edges of the cake layer into the whipped cream, so that they are flush with the cream. This will create a smooth, seamless dome on top of the cake.
Gently spread the reserved ½ cup of whipped cream over the entire cake to fill in any cracks and even out the surface. If necessary, refrigerate the cake to firm it up before continuing.
Dust your work surface with icing sugar and press the marzipan into a 6-inch (15 cm) disc (knead it a bit to warm it up first). Coat both sides with icing sugar and roll it out into a 14” (35½ cm) diameter circle less than 1/8” (3 mm) thick. Use plenty of icing sugar to prevent it from sticking. Alternatively, you can roll the marzipan out between two wide sheets of parchment paper (still use plenty of icing sugar).
Use the rolling pin to drape the rolled-out marzipan sheet over the cake and smooth it around the cake gently with your hands.
Trim the excess marzipan from the bottom of the cake with a paring knife or spatula blade.
Place the marzipan rose and in the middle of the cake. You could also make the leaves, I didn't have enough marzipan leftover so i didn't.
Put the cake on a presentation platter and be ready to get some oooooooooohs and Awwwwws.