Prick the base with a small metal fork. Place baking paper and ceramic beans inside. Bake it for fifteen minutes to stay crisp.

Melt your butter in a small frying pan. Add the sliced onions to the hot pan. Cook them until they are very soft and clear.

Crack your fresh eggs into a large bowl. Pour in the heavy double cream slowly. Whisk them together until the mixture is uniform.

Add the mustard powder to your egg liquid. Stir in half of your grated cheddar cheese. Add a pinch of salt and black pepper.

Spread the cooked onions over the baked pastry. Pour the egg and cheese mixture over them. Sprinkle the remaining cheese on the very top.

Place the tin into the preheated oven. Bake for twenty-five minutes until the top is golden. The center should have a slight wobble.