First of all, prepare the dough for the crêpes: beat the milk with the flour and separately beat the eggs, then add the eggs to the milk and let it rest in the fridge for at least 30 minutes.
In the meantime, prepare the filling: if you don't have it available, prepare the custard and let it cool down a bit.
Peel the apples and cut them into cubes.
Put the apples in a saucepan with butter, sugar, raisins, rum and cinnamon and cook for about ten minutes, stirring occasionally, then let these too cool.
Beat the eggs in a bowl.
After 30 minutes, take the dough and cook the crêpes, one at a time, pouring 1 ladle of batter on a lightly greased pan or non-stick pan with flat bottom: tilt and rotate the pan, so as to distribute the dough over the entire surface.
Once the surface is firm, gently turn the crepe with a spatula and cook the second side as well: as they are ready, stack your crêpes on a plate.
Fill the crêpes with a little apples and a little custard, then fold them in 4.
The apple crêpes are ready: decorate with a few more cubes of apple and serve.