prepare pasta according to package. drain & set aside. meanwhile, steam cauliflower in steamer basket over boiling water for 5 minutes. drain & set aside

whisk milk, cream, eggs, salt & cayenne in large heavy-bottomed saucepan, stir in cheese & mustard. set over medium heat

add pasta, cauliflower & butter, cook stirring constantly until sauce gets thick & smooth, about 5 minutes. meanwhile, heat broiler & place rack in medium of oven

transfer pasta to 8 inch square or 9 inch round ovensafe dish. broil for 2-3 minutes just until crust develops. serve immediately