Preheat oven 180C/350F.
Butter grease a 28cm/11inch pie dish.
In a pan fry the sliced onions in some butter.
When they start to soften add the spinach and cook until it wilts.
Turn off heat and leave to cool.
In a bowl combine beaten eggs with cream, 2 tablespoons parmesan cheese, basil, spinach filling, salt and pepper.
Pour mixture into your prepared pie dish.
In a small bowl combine ricotta with mozzarella and 2 tablespoons parmesan cheese.
Drop spoonfuls all around, top with cherry tomatoes and remaining parmesan cheese.
Bake in oven for approximately 1 hour or until set and golden on top.
Enjoy!