Prepare a one-crust pastry for a 9-inch pie. Beat together 1 cup half & half and 3 eggs. Add 1/2 teaspoon salt, a few grains of black pepper, and a few grains of cayenne pepper. Add 1 1/2 cups shredded Swiss cheese.

In a skillet, saute 1/2 cup chopped onion with 1/4 cup butter until golden, about 5 minutes. Add 1 (10 oz.) package frozen chopped spinach, thawed and well drained. Add 2 tablespoons chopped parsley, mix well. Remove from heat. Turn into large bowl.

Combine spinach and egg mixture, pour into pie shell. Bake at 425 degrees for 10 minutes, then 300 degrees for 40 to 50 minutes.

Slice 1 cup onion rings, saute in 2 teaspoons butter until golden. Arrange around edge of quiche, overlap slightly.