1. Brown 3 tablespoons butter for a moment in a medium hot skillet, adding onions cut in 1/4 inch slices of onion halves, thyme and 1/2 teaspoon salt.
2. Turn heat to low, stirring occasionally, cooking for about a half hour until onions are soft, but not browned or caramelized.
3. In a large bowl beat eggs lightly with a fork, adding yogurt, 1/4 teaspoon salt and a bit of pepper and nutmeg.
4. Preheat oven to 400 degrees. Add onions and most of the cheese to the large bowl, mix and pour into a buttered glass pie plate or four buttered gratin dishes. (you may also use a 9" springform).
5. Top with remaining cheese and sprinkle with a little more nutmeg. Bake for about 20-25 minutes, until surface is firm and slightly browned.
6. Serve with steamed baby carrots, a green salad and a bowl of fresh blueberries ad strawberries. Enjoy!