Preheat oven to 375 degrees F.
Mix together all ingredients except 2 tablespoons Cheddar to create a batter in a bowl.
In a 10-inch cast iron skillet melt butter. Saute onions and broccoli until soft. Pour batter over the vegetable mixture and sprinkle top evenly with remaining cheese. You can also place the ingredients in an 11 by 17-inch baking dish.
Bake in oven until golden, 30 minutes.
Recipe courtesy of The Neelys