To make your frittata
Heat the oil and gently fry the onion until soft but not brown.
Add the courgettes and cook on a low/medium heat for 5 minutes.
Add the peas and herbs to the mix.
Season the eggs with salt and pepper, add the milk and beat until smooth and then pour over the vegetables.
Reduce the heat and cook for 3-4 minutes.
Scatter cheese on top then pop under a medium grill for 5 minutes until the top is solid and golden brown.
Serve with a green salad.