Slice and brown onions with bacon strips for 20 minutes. Add flour and mix. Pour milk and cream and bring to a boil. Add egg stirring quickly and season with salt and pepper.
Preheat oven to 250°C (480°F). Put pastry in your oven dish. Prick with a fork. Pour onions top of the pastry. Bake for 15 minutes. Low down temperature to 220°C (425°F) and bake for another 10 minutes. Serve with a green salad or as a starter.