Preheat the oven to 180C/160C fan/gas 4. Lightly grease a 20cm square tin or casserole dish.
Layer the sliced onion, peppers and spinach in the dish and place in the oven for 10minutes to soften.
Meanwhile whisk the eggs with the cottage cheese. Chop the parsley and add to the egg mixture.
Take the vegetables out of the oven and put the egg mixture over. Bake for a further 20-25minutes, or until just set. Leave to cool a little before cutting into slices and serving with a fresh green salad.
Season with sea salt and black pepper.