Strawberry and cream cake: the recipe for a delicious dessert

Ingredients:

For the sponge cake:
4 eggs
120 g sugar
120 g flour
For the filling:
400 ml milk
4 egg yolks
Vanilla sugar
90 g sugar
40 g cornstarch
6 g gelatin sheets
300 ml whipped cream
1 tablespoon sugar
2 tablespoons mascarpone (optional)
20 g butter
500 g strawberries