### Instructions:
1. Cook the jumbo pasta shells according to package directions until al dente. Drain and rinse with cold water to prevent sticking. Set aside.
2. While the pasta is cooking, prepare the meat sauce. Heat olive oil in a large skillet or Dutch oven over medium heat. Add the chopped onion and cook until softened, about 5-7 minutes. Add the minced garlic and cook for another minute until fragrant.
3. Add the ground beef to the skillet. Break it up with a spoon and cook until browned, draining any excess fat.
4. Stir in the crushed tomatoes, tomato sauce, dried basil, dried oregano, and red pepper flakes (if using). Bring to a simmer, then reduce heat to low, cover, and let it cook for at least 15 minutes to allow the flavors to meld. Season with salt and pepper to taste.
5. In a medium bowl, combine the ricotta cheese, egg, 1/2 cup grated Parmesan cheese, chopped fresh parsley, salt, and pepper. Mix well until everything is thoroughly combined.
6. Preheat your oven to 375°F (190°C).
7. Spread a thin layer of the meat sauce on the bottom of a 9×13 inch baking dish.
8. Carefully fill each cooked pasta shell with a generous spoonful of the ricotta mixture.
9. Arrange the filled shells in a single layer in the prepared baking dish.
10. Pour the remaining meat sauce evenly over the stuffed shells.
11. Sprinkle with the shredded mozzarella cheese and a little extra grated Parmesan cheese.
12. Bake for 25-30 minutes, or until the cheese is melted and bubbly and the sauce is heated through.
13. Garnish with additional fresh parsley, if desired, before serving.
### Short Tips:
* **Don’t overcook the shells:** Al dente is key! They will continue to cook in the oven, and you want them to hold their shape.
* **Make ahead for ease:** You can assemble the stuffed shells a day in advance. Cover tightly and refrigerate. Add an extra 10-15 minutes to the baking time if baking from cold.
* **Freeze for later:** This recipe freezes beautifully! Assemble and then freeze before baking, or freeze leftovers. Thaw overnight in the refrigerator and bake as directed.
* **Spice it up:** For more heat, add a pinch more red pepper flakes to the meat sauce, or even a dash of your favorite hot sauce to the ricotta mixture.
* **Vary your cheese:** Feel free to experiment with different cheese blends! Provolone, Fontina, or even a smoked mozzarella would be delicious additions.
