2 1/4 cups water
3 Tbsp margarine
1/2 tsp salt
1/2 cup milk
2 1/2 cups mashed potato flakes
1/2 cup dairy sour cream
2 oz (1/2 cup) shredded cheddar cheese
Heat oven to 350 degrees. Lightly butter 1 1/2 quart casserole. In a medium saucepan, heat water, margarine, and salt to rolling boil. Remove from heat. Stir in milk and potato flakes.
Blend in egg, sour cream, and cheese, mixing throughly. Scoop or spoon into pre-pared casserole.
Bake at 350 degrees for 20 to 30 minutes until lightly golden brown and puffed.