Preheat the oven to 375 degrees. Grease a 9 inch deep dish pie plate with butter.

In a frying pan over medium heat, fry the bacon until crisp. Remove to a paper towel lined paper plate and allow the grease to drain.

Remove all but 1/2 Tablespoon of the grease from the frying pan. Add the onion and saute until soft and golden brown, about 7-8 minutes. Remove from the pan.

In a bowl, whisk together the eggs, half and half, salt, cayenne, and pepper. Stir in the Swiss cheese, 1/4 cup of the Parmesan cheese, onion, and bacon. Pour the mixture into the prepared pan. Sprinkle with the remaining Parmesan.

Bake for 35-45 minutes or until the quiche is golden brown and has just a slight jiggle in the center. Serve warm or at room temperature.