6 large Spanish onions
85 g gruyère or cheddar cheese
salt
pepper
1 egg
227 g flour
1 teaspoon salt
85 to 113 g butter
a little cold water for the mixture

Make a thin dough. Grease a baking dish and lay out the dough into it. Heat oil in a pan and simmer the chopped onion for about 25 minutes until light brown. Grate the cheese and mix with a beaten egg, salt and pepper. Add the onions and pour the mixture over the dough. Leave it to bake in the oven between 20 and 25 minutes.