Cooking Instructions:

Preheat your oven to 375°F (190°C). Bring a large pot of salted water to a boil and cook the jumbo pasta shells until al dente. Drain and set aside to cool slightly.

In a mixing bowl, combine ricotta cheese, half of the mozzarella cheese, parmesan cheese, egg, salt, and pepper. If you're adding any meat or vegetables, incorporate them into the mixture at this point.

Carefully fill each cooked pasta shell with the cheese mixture. Spread a thin layer of marinara sauce on the bottom of a baking dish to prevent sticking.

Place the stuffed shells in the baking dish, seam side up. Once all shells are filled, pour the remaining marinara sauce over the top and sprinkle with the remaining mozzarella cheese.

Cover the dish with aluminum foil and bake in the preheated oven for 20 minutes. After that, remove the foil and bake for an additional 10-15 minutes, or until the cheese is melted and bubbly.

For a golden finish, switch on the broiler for a few minutes, keeping a close eye to prevent burning. Once done, remove from the oven and let the dish cool slightly before serving.

Extra Tips:

For best results, make certain that the pasta shells aren't overcooked during boiling, as they'll continue to cook in the oven.

You can also prepare the stuffed shells in advance and refrigerate them for later use or freeze them for up to three months. If baking from frozen, adjust the cooking time and temperature accordingly, starting at a lower heat to guarantee even baking throughout.

Finally, feel free to experiment with different cheese combinations and fillings to create your perfect stuffed shells!