In a large frying pan, brown sausage with onion and pepper, stirring to crumble sausage. Drain. In a large bowl, mix all remaining ingredients (except salsa), and stir in sausage mixture. Transfer to a greased 13� x 9" baking dish. Sprinkle extra cheddar cheese on top if desired. Bake at 350�F for 35 to 40 minutes. Delicious served with a spoonful of salsa.