Cottage And Cheddar Cheese Spinach Breakfast Casserole

3/4 cup chopped onion
1/4 cup flour
6 beaten eggs
16 ounces cottage cheese
16 ounces cheddar cheese, shredded
1/2 cup butter, melted
10 ounces frozen spinach, thawed and drained
salt and pepper to taste

Grease a 9x13 inch baking dish with cooking spray while preheating oven to 350 degrees.
In a medium sized mixing bowl, beat the onion, flour and eggs until it's smooth and not lumpy.
Add in the cottage cheese, cheddar cheese, butter, spinach, salt and pepper and stir until mixed thoroughly. Pour into the prepared dish.
Bake for approximately 45 to 50 minutes or until casserole is golden brown and bubbly.