Creating the Sloppy Joe Pierogi Casserole is straightforward if you follow these simple steps:

1. Preheat the Oven: Preheat your oven to 350°F (175°C).
2. Cook the Meat: In a large skillet, heat olive oil over medium heat. Add the diced onion and red bell pepper, sautéing until softened.
3. Add Garlic: Stir in the minced garlic and cook for an additional minute.
4. Brown the Beef: Add the ground beef to the skillet. Cook until browned, breaking it up with a spoon.
5. Season the Mixture: Stir in Worcestershire sauce, mustard, Sloppy Joe sauce, salt, and pepper. Let the mixture simmer for about 5 minutes.
6. Prepare the Casserole Dish: In a greased 9×13-inch baking dish, spread half of the frozen pierogi in an even layer.
7. Layer the Meat Mixture: Pour the Sloppy Joe mixture over the first layer of pierogi, spreading it evenly.
8. Add Cheese: Sprinkle 1 cup of shredded cheddar cheese over the meat mixture.
9. Top with Remaining Pierogi: Layer the remaining pierogi on top of the cheese.
10. Finish with Cheese: Top with the remaining cup of cheddar cheese.
11. Bake: Cover the dish with aluminum foil and bake in the preheated oven for 30 minutes. Then, remove the foil and bake for an additional 15 minutes until the cheese is bubbly and golden.
12. Cool and Garnish: Once baked, let the casserole cool for a few minutes. Garnish with chopped parsley before serving.

These steps will guide you in creating this incredible casserole effortlessly.