Step 1.  Get out an 11 x 8 inch or 9 x 9-inch casserole dish.

Step 2.  Boil a large pot of salted water.  Add pasta and cook for 10 minutes.  Drain.  Add pasta to a large bowl.

Step 3.  In a medium-sized saucepan, over Medium heat, melt together butter, cream cheese and heavy whipping cream.  Stir until completely melted with no clumps of cream cheese left.

Step 4.  Stir in 1 1/4 cup cheddar, 1 cup mozzarella, and 1 cup parmesan cheese and cook until fully melted and smooth.

Step 5.  Remove from the heat and stir in the paprika.  Taste for salt and add salt and pepper if desired.  How much salt you need will depend on how salty the cheese you use is.

Step 6.  Pour the cheese sauce into the bowl of pasta and mix to combine.  Pour the mixture into the casserole dish. 

Step 7.  Top with remaining 1/2 cup cheddar cheese and heat under the broiler for 1-2 minutes until cheese is melted.  If you like it browned on top, then you can broil it for 3-4 minutes.  Keep a close eye on it though, because it will go from browned to burnt very quickly.