Preheat oven to 375 degrees.  Rub softened butter onto the bottom and sides of cast iron or oven proof skillet.  Place 8 biscuits into the bottom of prepared skillet.  Put 2 quarters of cheddar cheese on each biscuit.  Divide sausage evenly between the 8 biscuits and pile it on each.  Divide shredded mozzarella cheese on top of sausage.  Bake for 20-25 minutes for refrigerated biscuits or 25-30 minutes for frozen biscuits.  The biscuits will be golden brown around the edges.  Serve warm.  Store in an airtight container, refrigerated and warm in microwave for 30 seconds to warm-up.