First Step: PREPARE THE PASTA SHELLS

1. Cook the Pasta: Begin by boiling the jumbo pasta shells according to the package instructions. Be sure to cook them al dente, as they will continue cooking in the oven. Once cooked, drain the shells and set them aside to cool slightly. Drizzle with a bit of olive oil to prevent them from sticking together.
2. Prepare for Stuffing: Lay the cooked shells on a baking sheet or tray to cool down before stuffing. This will make it easier to handle the shells without burning your hands.

Second Step: MAKE THE GROUND BEEF FILLING

1. Sauté the Onion and Garlic: Heat 1 tablespoon of olive oil in a large skillet over medium heat. Add the chopped onion and cook until softened and translucent, about 5 minutes. Add the minced garlic and cook for another 1-2 minutes until fragrant.
2. Cook the Ground Beef: Add the ground beef to the skillet, breaking it up with a spoon as it cooks. Cook until browned and cooked through, about 8-10 minutes. Drain any excess fat, if necessary.
3. Season the Beef: Add the oregano, basil, salt, and pepper to the cooked beef mixture, stirring to combine. Taste and adjust the seasoning if necessary. Remove from heat and allow the mixture to cool slightly.
4. Prepare the Cheese Mixture: In a separate bowl, combine the ricotta cheese, shredded mozzarella cheese, and egg. Mix until smooth and well combined. Add the cheese mixture to the cooled beef mixture and stir until everything is evenly incorporated.

Third Step: MAKE THE MARINARA SAUCE

1. Sauté the Onion and Garlic: In a large saucepan, heat 1 tablespoon of olive oil over medium heat. Add the chopped onion and cook until softened, about 5 minutes. Add the minced garlic and cook for another 1-2 minutes, until fragrant.
2. Add the Tomatoes: Pour in the crushed tomatoes, stirring to combine. Add the oregano, basil, sugar, salt, and pepper. Simmer the sauce over low heat for about 20-30 minutes, stirring occasionally, until the flavors have melded together. Adjust the seasoning if necessary.
3. Finish the Sauce: Stir in the chopped parsley right before serving for a fresh touch. Set aside to use for topping the stuffed shells.

Fourth Step: STUFF THE PASTA SHELLS

1. Stuff the Shells: Preheat your oven to 375°F (190°C). Carefully stuff each cooked pasta shell with the ground beef and cheese mixture, being sure to fill them generously. Place the stuffed shells in a large baking dish, arranging them in a single layer.
2. Top with Sauce: Pour the prepared marinara sauce over the stuffed shells, covering them generously. Make sure the shells are well-coated to prevent them from drying out during baking.
3. Add Extra Cheese: Sprinkle the remaining shredded mozzarella cheese on top of the sauce-covered shells for an extra cheesy topping.

Fifth Step: BAKE THE STUFFED SHELLS

1. Cover and Bake: Cover the baking dish with aluminum foil and place it in the preheated oven. Bake for about 25-30 minutes, or until the cheese has melted and the dish is bubbly.
2. Uncover and Brown the Top: After 25-30 minutes, remove the foil and continue baking for an additional 10-15 minutes, or until the top is golden and slightly crispy.

Final Step: GARNISH AND SERVE

1. Garnish: Once baked, remove the stuffed shells from the oven and let them cool for a few minutes. Garnish with fresh basil leaves and a sprinkle of grated Parmesan cheese.
2. Serve: Serve the stuffed shells hot, with extra marinara sauce on the side if desired. Pair with a light salad or crusty bread for a complete meal.