Preheat oven to 350 degrees. Line muffin tin with 12 paper muffin cup liners or lightly spray with non-stick spray.
In a medium skillet, cook turkey sausage, breaking up into small pieces as it cooks. Cook until no pink remains. Add green pepper and onion to the sausage and cook until soft.
Divide bread cubes between 12 muffin cups. Spoon turkey sausage mixture on top of bread crumbs and cheese on top of the turkey mix. Only fill cups about 3/4 full.
In a bowl, whisk together egg whites, eggs, milk, and salt. Pour over bread, sausage, and cheese-filled muffin cups. Only fill to just cover the ingredients in the muffin cups. Allow to rest for 5 minutes and add more egg mix to the cups if needed.
Bake for 15 to 20 minutes until set in the middle and tops begin to brown. Allow to rest for 5 minutes before removing from muffin tin. Serve warm.