Melt butter and cook shrimp slowly on low heat. When shrimp are pink in color remove and set aside. In melted butter add cream cheese and whipping cream. Heat and stir until cream cheese is melted and mixture is smooth. Add seasonings to taste and Parmesan cheese. Combine cornstarch with a small amount of water. Add to sauce to thicken. Add shrimp again. Serve over cooked fettucini.