FoodHopp

Name: Traditional Tarte aux Poireaux from France
Prep time: 25 min
Cook time: 35 min
Yield: 4
Cuisine: France
Ingredients: 250g (8 oz) unsalted butter; 3 large onions, finely chopped; 1 cup whole milk; 2 eggs; 200g (7 oz) Gruyère cheese, grated; 100g (3.5 oz) Parmesan cheese, grated; 250g (9 oz) puff pastry, thawed; 1 egg, beaten for brushing