Add the sausage to a medium saute pan.Cook over medium-high heat until browned, crumbling the sausage with a spoon as it cooks.Remove sausage with a slotted spoon and transfer to a large mixing bowl.Reserve about 1 tablespoon of sausage grease in the saute pan, discarding the rest.Add the onion, green pepper and red pepper to the saute pan, and saute for 5 minutes until cooked.Add the garlic and saute for an additional 2 minutes until fragrant.Pour the vegetable mixture into the mixing bowl with the sausage.Add the hash browns and 1½ cups cheese to the mixing bowl with the sausage and veggies. Stir to combine.In a separate bowl, whisk together the eggs, milk and black pepper until combined.Then add them to the hashbrown mixture, and stir to combine.Pour the mixture into a baking dish, and top with the remaining ½ cup of shredded cheese.Cover with aluminum foil and bake for 20 minutes.Then remove the aluminum foil and bake for an additional 10-15 minutes and the top of the potatoes begin to slightly brown.Remove and let the casserole rest for 5 minutes.