MELT BUTTER IN A SAUCEPAN OVER MEDIUM HEAT. STIR IN FLOUR. GRADUALLY STIR IN BROTH. HEAT TO BOILING, STIRRING CONSTANTLY; REDUCE HEAT TO LOW. STIR IN MASCARPONE, WHITE CHEDDAR CHEESE, GOUDA, PARMESAN AND HALF-AND-HALF. ALLOW ALL CHEESE TO MELT AND MELD TOGETHER WHILE CONTINUOUSLY STIRRING. ONCE COMPLETELY MIXED TOGETHER AND CHEESE IS MELTED, STIR IN CHICKEN.