Prepare desired quantity of mash potatoes as directed on the box. (prefer Hungry Jack Idaho) remove from heat and place in bowl.
Spray aa 9x13 glass dish with cooking spray
In a separate bowl mix the 1/2 of each package of cheese, stick of margarine, green onions, black pepper and garlic powder and evaported milk. (use more or less black pepper and garlic powder according to your taste)
Combine cheese mixture with potatoes and spoon into the glass dish.
Top with bacon bits and the remaining cheese.
Bake for 30 minutes covered with foil on middle rack. Remove foil, and bake for another 10 to 15 minutes or until top is slightly browned.