Preheat your oven to 425 degrees F.

Place the sliced onions and butter in casserole dish (I used an 8 x 8 baking dish) and microwave on high for 6 minutes, stirring every two minutes. Keep the lid on the dish so the onions steam a little bit. You can also do this part in a skillet on the stove if you prefer.

After the onions have cooked, they may have released a lot of juice, so you might want to drain some off, if there is too much the dish will be runny.

Meanwhile, in another dish beat the eggs lightly, then mix in the cream, salt and pepper.

Stir in any little bits of extra cheese if you wish.

Then pour the egg mixture over the cooked onions.

Cover with the parmesan cheese and bake, uncovered for about 15 - 20 minutes, or until the crust is golden brown and bubbling.