Amish Sausage Breakfast Casserole

1 onion, chopped
1 package sausage
4 cups hash brown potatoes
6 eggs
2 cups cheddar cheese, shredded
1 1/4 cups Swiss cheese
1 1/2 cups cottage cheese

Over medium-high heat in a large skillet, cook the onion and sausage until browned. Drain the grease and set aside.
In a medium mixing bowl, add the remaining ingredients and stir until thoroughly combined. Add the sausage and onion mixture.
Place all this into a 9x13 inch baking dish.
Bake at 350 degrees for 35 to 40 minutes or until bubbly. Before serving, let stand for 10 minutes.