Preheat oven to 375°F (190°C). Grease a 9×13-inch baking dish.
In a skillet over medium heat, cook the breakfast sausage until browned. Drain excess grease.
Sprinkle the flour over the cooked sausage and stir to coat. Cook for 1 minute.
Gradually pour in the milk while stirring. Add salt, pepper, garlic powder, and onion powder. Simmer for 2-3 minutes until thickened. Remove from heat.
In a large bowl, mix the hashbrowns with half of the shredded cheddar cheese.
Spread the hashbrown mixture evenly into the prepared baking dish. Pour the sausage gravy over the top.
Arrange the biscuit pieces over the gravy and brush them with melted butter.
Sprinkle the remaining cheddar and mozzarella cheese over the biscuits.
Bake for 30-35 minutes or until the biscuits are golden brown and the cheese is melted.
Garnish with fresh parsley and serve warm.