Melt the butter and olive oil in a medium skillet over medium heat, add the onions and cook for about 10 to 12 minutes or until golden brown, stirring occasionally.
Preheat the oven to 375 F.
Place all the ingredients in a medium bowl and mix well.
Divide mixture equally into greased ramekins or individual oven proof dishes and bake for about 20 minutes or until tops are puffed and set.