Cook cavatappi pasta according to package directions so it is al dente, drain, add 1 Tbsp of butter while still hot, and mix through; set aside to cool mostly. In a large sauce pan, melt butter into cream over low heat. Add garlic salt and pepper to taste. Stir in the pecorino romano and parmesan cheese over medium heat until melted; this will thicken the sauce. Remove from heat and allow to cool mostly. Once both noodles and sauce are just slightly warm, stir the sauce into the noodles. Add 3 cups of cheddar cheese and mix. Smooth into a 13x9x2 baking dish. Sprinkle top with the remaining cup of cheddar cheese. Bake at 350 degrees F for 30 minutes or until top starts to brown slightly.