Mix the flour, egg yolk, mineral water and oil (add a little salt) into a smooth dough.
Form a ball, wrap in foil and place in the refrigerator for 30 minutes.
Preheat baking oven to 230 °.
Line the baking sheet with parchment paper.
Chop the onions and spring onions into small pieces.
Mix the crème fraiche and milk with a little salt.
Roll out the dough thinly on a floured surface and place on the baking paper.
Spread the pastry thinly with the cream.
Then spread the diced ham with the onions.
Then sprinkle the grated cheese on top.
Turn the oven to 220 ° and bake the cake for about 15 minutes.
I took the recipe from a newspaper, the original is the cake without cheese. However, we like it with cheese, so the recipe has been modified to suit our taste.