Meanwhile, in 3-quart saucepan, melt 2 tablespoons of the butter over medium-high heat. Add flour; cook 1 minute, stirring constantly. Slowly add milk, stirring constantly. Heat to boiling; cook and stir until mixture thickens. Add Swiss cheese, salt and pepper; stir until cheese is melted. Stir in ham and cooked potatoes. Spoon mixture into frozen pie crust. Place in 9 1/2-inch deep dish pie plate or on cookie sheet. Bake 20 minutes.