Not really a recipe as such, but this is how I make one:
Heat oven to 175C, 375F or gas mark 5.
Butter an ovenproof dish (I use a Le Creuset ceramic dish 20cm square).
Beat 6 large eggs in a bowl, add 275ml double cream and beat well. Season with black pepper and a little salt then leave to stand while you prepare the other ingredients.
Grate 100g cheese. Cheddar is good or a mix of cheddar, mozzarella, red Leicester or whatever's in your fridge.
Chop up a combination of any of the following and fry in a little butter: pancetta, onions, garlic, red/green peppers, mushrooms, courgettes, leeks. You can also use left-overs of cooked food including broccoli, cauliflower, sprouts, broad beans, peas, ham, chicken, salmon.
Spread fried ingredients across base of dish, cover with grated cheese and pour over the egg/cream mixture. Grate a little nutmeg over the top.
Cook for about 30/35 mins until set and golden brown. Timing will vary depending on the size/depth of your dish and your oven; check after 30 mins and cook for longer if necessary.
Remove from oven and leave to stand for 10 minutes before eating.