Preheat the oven to 350 degrees F (175 degrees C).
Cook and stir bacon and onion in a skillet over medium heat until bacon is crisp, 10 to 15 minutes. Drain grease, reserving drippings.
Grease a 9x13-inch baking dish with reserved bacon grease.
Combine cooked bacon and onion, eggs, hash brown potatoes, Cheddar cheese, cottage cheese, Swiss cheese, bell pepper, and green chiles in the prepared baking dish; stir to combine.
Bake in the preheated oven until eggs are set firm, 35 to 40 minutes.
Let casserole cool 10 minutes before cutting to serve.