Preheat oven to 200°C.
Panfry chopped onion in olive oil until translucent (8-10 minutes).
Add crushed garlic and cook a further 2 minutes or until fragrant.
Defrost frozen spinach (I do this in the microwave) then press out the extra liquid. You don't have to get every last bit out, but it certainly shouldn't be dripping in liquid.
Add spinach and prosciutto to the onion and garlic stir and cook a further 2 minutes.
Add salt and chilli flakes mixing through. Turn off heat and let it cool slightly.
In a bowl whisk eggs, add cream and then when well combine mix through the grated cheese.
Add the onion and spinach mix to the egg mixture, combine.
Pour into a pie dish.
Bake in the preheated oven for 25-35 minutes. It will be ready when browned at edges and solid in the centre.
Wait 2-5 minutes before cutting. Serve warm with salad.