1. Cook onion in butter until soft.
2. Let cool.
3. Spread onions into pre-cooked quiche shell.
4. Cook broccoli in salted boiling water and drain.
5. Cook mushrooms in 1 tbsp. butter.
6. Add mushrooms and broccoli to quiche.
7. Sprinkle with Parmesan.
8. Beat eggs. Add cream and milk and season the mixture with salt, pepper and nutmeg. Pour on top of cheese.
9. Bake for 35-40 minutes in pre-heated 250 C oven.