1. Fry the butter, bacon, onion and spinach together.
2. Season with black pepper and whipping cream. Stir until the cream is stronger then turn off the stove and leave to cool.
3. Put cold filling into the pie. Sprinkle with Parmesan cheese and mozzarella cheese. Bake at 200 degrees for 15-20 minutes.
4. When finished, leave it cool first before cut the pie.