Preheat oven to 450°F. Heat hash browns in microwave for 30 seconds so they're more pliable. In a large bowl, combine the hash browns, 1/2 cup cheese, and season with salt and pepper. Grease a 12 cup muffin tin with cooking spray. Divide the hash brown mixture evenly in the muffin cups. Use your fingers to pack them tightly and shape them into nests.
Bake for 20 minutes or until the edges have browned. Remove the hash browns from the oven and reduce temperature to 350°F.
In a large mixing bowl, combine eggs and milk and whisk until eggs are beaten. Stir in 1 cup cheese, bacon, pepper, onion, salt and black pepper.
Divide mixture evenly in the 12 hash brown nests. Sprinkle each with remaining 1/2 cup cheddar. Bake for 20-25 minutes or until centers are set and top is beginning to brown. (These can be eaten now or frozen and warmed up in microwave later)