Preheat oven to 400* Grease a 9 x 13 cookie sheet. Mix the first 3 ingredients well, add the frozen Pierogies and toss to evenly coat. Place the all Pierogies in single layer on baking sheet, (All facing up the same direction, makes it easier to know which ones you flipped after the first 10 minutes cooking) -Bake 20 minutes, flipping over half way through. Serve immediately with a side of sour cream for dipping.