Kielbassa-Potato Casserole

• 1 pkg Scalloped Potato Mix (5.25 oz.) - Betty Crocker, Hungry Jack or similar product
• 2 cups boiling water
• 2 T. margerine
• 2/3 cup milk
• 1 medium onion - finely chopped
• 1 lb. Kielbassa

Preparation -
In an oblong glass baking dish, mix potatoes, sauce mix, boiling water, margerine and milk. Stir in chopped onion. Slice kielbassa diagonally into 1/4" to 1/2" thick slices.Arrange slices in rows on top of potato mixture. Bake at 375º for 35 to 40 minutes. Let stand a few minutes before serving.