In France this is really easy to make, as they sell round, readymade puff pastry. Otherwise for regular pie dough, mix 2 parts flour with 1 part oil or butter. Add a pinch of salt and enough cold water to knead into a ball that hangs together. Roll out on a floured board to fit the greased mould.
For the filling, stir-fry your vegetables (leeks, cauliflower, broccoli, etc) until half done. Mix eggs with crème fraîche, or some milk or water. Cover the bottom of the dough with a layer of breadcrumbs to avoid its getting soggy. Spread the vegetables on top, then pour the egg mixture over it. Sprinkle with some grated cheese if you like. Slide into a preheated 200º C oven and bake until golden. 30-40 minutes.
Serve with a leafy salad.