Sauté onion in oil in skillet over medium heat until softened (approx. 3 minutes). Add spinach and cook until wilted, then stir in the ham, chives, and pepper flakes. Transfer spinach mixture to pre-baked crust, and place on baking sheet. Pour in egg mixture into crust.
Sprinkle with:
1/4 cup Fontina cheese - shredded
Sprinkle quiche with fontina cheese and bake in oven 35-40 minutes, or until filling is set in the center