Bring potatoes to a boil. Cook until done (soft) and drain. Be sure to reserve 1 cup of the potato water.Melt butter and saute onions.Next, stir in flour and pepper until smooth.Gradually add the milk product and reserved potato water, while stirring.Bring to a boil. Boil until thick.Remove from heat and add cheese. Stir until melted.Add cooked potatoes.ENJOY!