1 tablespoonthinly sliced fresh basil, for garnish
Preheat oven to 350 degrees. Drizzle a large skillet with oil, arrange pierogies in a single layer (edges can be overlapping a bit).
Pour water over the pierogies. Bring to a simmer over medium-high heat and cook for 3 minutes, then flip pierogies over and cook another 2-3 minutes until tender and easily pierced through with fork. Drain liquid from skillet.
Spoon pesto on top of the pierogies, then sprinkle with shredded mozzarella. Bake for 10 minutes until cheese is completely melted. Top with tomatoes and fresh basil and serve immediately.
Flavor option: swap these for other flavors of pierogies - they all work with this recipe!