1.Place Sausage In A Microwave-Safe Bowl. Microwave, Uncovered, On High For 3 Minutes. Drain And Set Aside. 2.Place Butter In A 2-1/2-Qt. Microwave-Safe Dish. Heat On High For 45-60 Seconds Or Until Melted. Whisk In Flour, Salt And Pepper Until Smooth. Gradually Whisk In Milk. Microwave, Uncovered, On High For 8-10 Minutes Or Until Thickened And Bubbly, Stirring Every 2 Minutes. 3.Stir In Potatoes And Onion. Cover And Microwave On High For 4 Minutes; Stir. Heat 4 Minutes Longer. Stir In The Sausage. Cover And Cook For 8-10 Minutes, Stirring Every 4 Minutes Or Until Potatoes Are Tender And Sausage Is Heated Through. Stir. Let Stand, Covered, For 5 Minutes. Sprinkle With Parsley If Desired.