Tuscan pine nut cake

Make it as the first thing, as you'll need it to be cold when you will add it to the cake. Heat the milk in a saucepan until it starts to simmer, then set aside.
Whisk the egg yolks with the sugar and the flour, then pour in the hot milk in a thin stream, stirring continuously with a whisk.
Transfer the pastry cream to the saucepan and move it on a low flame. Stir it constantly until it begins to thicken, about 3 minutes. Remove it from the heat, add the raisins and let it cool down.

Preheat oven to 175°C/350 degrees F.
Wisk butter and sugar for a few minutes, until creamy and light.
Add the eggs gradually, one after the other, waiting for the first to be completely incorporated before adding the next one.
Stir in the flour sifted with the baking powder.
Grease and dust with flour a 22cm/9in round cake pan.
Separate the batter equally into two pastry bags. Pipe the batter of the first pastry bag onto the cake pan, then spread it evenly with a spatula.
Spoon the cold pastry cream over the first layer of cake, leaving 2 cm all around the edges. Smooth the surface of the pastry cream.
Pipe the batter of the second pastry bag on top of the pastry cream in concentric circles, trying not to mix it with the custard, then spread it evenly with a spatula. Sprinkle the surface with pine nuts.
Transfer to the oven and bake for 45 to 50 minutes, until golden brown.
Remove the cake from the oven, let it cool down completely, then gently unmould it onto a plate. Keep in the fridge for a few hours before slicing in.