Mix the first six ingredients well. Saute onion and drain the spinach until almost completely dry. Fold spinach, onion and cheese with the egg mixture.
Pour into greased 11x15 glass baking dish. At this point you can add (optional) several slices of pre-cooked Bacon on top of casserole(cut in pieces). Bake at 350F for 30 to 45 minutes or until set and a knife comes out clean.
If you do not have a large pan and want to use 13x9 change the ingredients to:
12 oz cottage cheese
½ stick melted butter
8 oz cream cheese softened
8 oz sour cream
2 tablespoons AP flour
2 cups Monterey/Colby shredded cheese
One 9 oz frozen chopped spinach
Onion and Salt and Pepper to taste