Melt butter in 2-quart saucepan over medium heat. Add enough additional flour to remaining flour mixture to make 2 tablespoons. Stir flour mixture into butter. Cook, stirring constantly, until mixture is smooth and bubbly; remove from heat. Gradually stir in half-and-half and broth. Heat to boiling, stirring constantly. Boil and stir 1 minute. Stir in sherry and oregano. Pour evenly over pheasants.