Preheat the oven to 350 degrees Fahrenheit, spray a 9 x 13 x 2-inch or 3-quart baking dish with pan spray, and set aside.
Dice 1 pound baconand cook in a large skillet over medium-high heat until most of the bacon is crisp.
Add 1 ½ cups diced onion, to the skillet and cook it with the bacon for 2-3 minutes, until it begins to turn translucent. Add 2 teaspoons minced garlic, and cook for 1 more minute. Use a slotted spoon to remove it from the pan and transfer it to a paper towel-lined bowl or plate to drain.
Combine 6 large eggs,3 cups shredded hash browns, 2 cups shredded cheddar cheese, 1 cup shredded swiss cheese, 1 ½ cup small curd cottage cheese, ½ teaspoon salt, and ¼ teaspoon ground black pepper in a large bowl.
Stir in the bacon mixture, then transfer everything into the prepared baking dish. If desired, top with a handful of additional cheddar and Swiss.
Bake for 45-50 minutes, until all the cheese is melted and a knife comes out clean from the center. Let the casserole sit for 10 minutes before serving.