Sponge Cake:

1. Preheat your oven to 350°F (175°C). Grease and flour a 9-inch round cake pan.
2. Beat eggs and sugar together until pale and fluffy. Add vanilla extract.
3. Gently fold in the sifted flour until just combined.
4. Pour the batter into the prepared pan and bake for 20-25 minutes or until a toothpick inserted into the center comes out clean.
5. Let the cake cool completely, then slice horizontally into two or three layers.

Syrup:

1. Combine sugar and water (and lemon juice or cinnamon, if using) in a saucepan. Bring to a boil, then simmer for about 5 minutes. Let cool.

Egg Yolk Cream:

1. Whisk egg yolks, sugar, and water in a heatproof bowl.
2. Place the bowl over a pot of simmering water (double boiler method), whisking constantly until the mixture thickens.
3. Remove from heat and let the cream cool.

Marzipan:

1. Mix almond flour and powdered sugar in a bowl.
2. Gradually add egg whites and almond extract, kneading until a smooth dough forms.
3. Roll out the marzipan between two sheets of parchment paper to the size needed to cover the cake.

Assembly:

1. Place the bottom layer of sponge cake on a serving plate. Brush generously with the syrup.
2. Spread a layer of egg yolk cream over the moist sponge.
3. Add the next layer of sponge cake and repeat the syrup and cream layers until all sponge layers are used.
4. Cover the entire cake with the rolled-out marzipan, trimming any excess.
5. Optional: For a traditional finish, lightly torch the marzipan or dust with powdered sugar.