Creating Sloppy Joe Pierogi Casserole is simple. Just follow these steps:

1. Preheat the Oven: Preheat your oven to 350°F (175°C).
2. Cook the Beef: In a large skillet, heat olive oil over medium heat. Add diced onion and ground beef. Cook until the beef is browned and the onion is tender, about 5-7 minutes.
3. Add Sauce: Drain excess fat, then stir in the Sloppy Joe sauce, garlic powder, salt, and pepper. Let it simmer for 3-5 minutes until heated through.
4. Prepare the Casserole Dish: In a greased 9×13-inch baking dish, spread half of the frozen pierogi in a single layer.
5. Layer the Meat Mixture: Spoon the Sloppy Joe mixture evenly over the layer of pierogi.
6. Add Cheese: Sprinkle 1 cup of shredded cheddar cheese over the meat mixture.
7. Top with Remaining Pierogi: Layer the remaining pierogi on top of the cheese, followed by the rest of the Sloppy Joe mixture.
8. Final Cheese Layer: Top with the remaining 1 cup of shredded cheddar cheese.
9. Bake: Cover the dish with aluminum foil and bake for 25 minutes. Remove the foil and bake for an additional 5-10 minutes, or until the cheese is melted and bubbly.
10. Garnish: Remove the casserole from the oven and let it cool for a few minutes. Garnish with chopped green onions or parsley, if desired.

These easy steps lead you to a delicious Sloppy Joe Pierogi Casserole that is sure to satisfy.