Melt butter in a skillet. Add onions and cook until soft but not browned.Place mashed potatoes, cheeses, sour cream in a bowl. Add sautéed onions. Season aggressively with salt and pepper and mix thoroughly. Chill the filling mixture in the refrigerator for about 1/2 hour before filling.These pierogi may be served boiled, or boiled and drained then added to a skillet and browned in butter on both sides. Serve with sour cream or applesauce, and garnish with caramelized onions.
Keyword pierogi filling ideas, potato and cheese pierogi recipe