Preheat the oven to 190°C.
Lightly oil a muffin tin.
Finely chop the chipolatas and spring onion. Grate the courgette or chop the mushrooms.
Beat the eggs in a bowl. Add the courgette.
Chop the herbs, and chilli (if used) and mince the garlic. Add these to the egg mixture, season with salt and pepper, then toss gently.
Spoon the batter in the muffin tin, filling each cup ¾ full (at this point you can grate some Cheddar on top if you like).
Bake in the oven for about 20 minutes until golden.
Let them cool in the tin for a couple of minutes, then transfer them to a plate and serve with a salad. Alternatively, let them cool completely and serve them as snacks or party nibbles.