Let’s get cooking! Here’s a step-by-step guide to crafting these delicious stuffed shells:

1. Preheat your oven to 375°F (190°C). Grease a large baking dish with a bit of olive oil to prevent sticking.
2. Cook the jumbo shells according to the package instructions until al dente. Drain and set aside.
3. In a large skillet, heat the olive oil over medium heat. Add the chopped onion and cook until translucent, about 5 minutes.
4. Add the minced garlic to the skillet and sauté for another minute until fragrant.
5. Add the ground beef, Italian seasoning, salt, and pepper. Cook until the beef is browned and fully cooked, breaking it apart with a spoon, about 8-10 minutes.
6. In a large mixing bowl, combine ricotta cheese, 1 cup mozzarella, and Parmesan cheese. Stir in the cooked beef mixture.
7. Spread 1 cup of marinara sauce evenly over the bottom of the prepared baking dish.
8. Stuff each cooked shell with the beef and cheese mixture, placing them in the baking dish open side up.
9. Pour the remaining marinara sauce over the shells, ensuring each is well-covered.
10. Sprinkle extra mozzarella cheese on top for a cheesy finish.
11. Cover the dish with aluminum foil and bake for 25 minutes. Then, remove the foil and bake for an additional 10 minutes until the cheese is bubbly and golden.
12. Garnish with fresh basil leaves before serving for a burst of color and freshness.

This might seem like a lot of steps, but trust me, it’s an easy process that yields a big payoff. Nothing beats the satisfaction of pulling a bubbling dish of stuffed shells from the oven!