Or what the French would call a tarte aux poireaux.
You need to make some shortcrust pastry and line a large tart dish with a removable base.
Then, blind bake the pastry and while that is in the oven, sauté some sliced leeks in butter and olive oil. Make sure that you don’t let them brown or they will go bitter. What we want is the sweetness of the softened leeks.
Take a tub of fromage frais, two large eggs, some grated Emmenthal or Gruyère cheese, some dried fines herbes (although fresh herbs would be better), salt and pepper and mix all these together in a bowl.
Spread the leeks across the tart base and pour over the cheese and egg filling.
Top with some more grated cheese and bake in the oven at Mark 6/180C until the pastry is done and the filling has set into a custard. The top should also be golden.
You can eat this warm or at room temperature. Let it cool slightly before removing the ring from the tart.
All it really needs to accompany it is a nice salad.