Grandmother's New Potatoes with Parsley Recipe

Boil potatoes in salt water until they can be penetrated with a fork; do not overcook. Drain water off and put back into saucepan. Melt butter in a saucepan over medium heat. Add flour, salt and pepper. Cook, stirring constantly until well mixed. Slowly pour in milk and stir well. Add white sauce back to potatoes in pan. Flour and milk may need to be adjusted, depending on desired thickness of sauce. Sprinkle in parsley before serving.