Twice Baked Potato Dump Casserole

40min · 12 servings Ingredients • 2 24 ounce packages refrigerated mashed potatoes • 8 ounce shredded cheddar cheese (2 cups) • 1 medium onion, finely chopped (1 cup) • 1 cup sour cream • 6 slices ready-to-serve cooked bacon, chopped • ¼ cup chopped fresh chives • 4 cloves garlic, minced • ½ teaspoon ground black pepper