In a large pot of boiling salted water, cook the jumbo pasta shells according to package instructions until al dente. Drain and set aside.
In a skillet over medium heat, cook the ground beef until browned and cooked through. Add minced garlic and cook for an additional 1-2 minutes until fragrant. Season with salt, pepper, and Italian seasoning.
In a mixing bowl, combine the cooked beef, ricotta cheese, half of the mozzarella cheese, Parmesan cheese, and egg. Mix until well combined.
Carefully stuff each cooked shell with the beef and cheese mixture.
Spread half of the marinara sauce on the bottom of a baking dish. Arrange the stuffed shells in a single layer on top of the sauce.
Pour the remaining marinara sauce over the stuffed shells and sprinkle with the remaining mozzarella cheese.
Cover the dish with aluminum foil and bake in the preheated oven for 25 minutes.
Remove the foil and bake for an additional 10 minutes, or until the cheese is bubbly and golden.
Once baked, remove from the oven and let sit for a few minutes. Garnish with fresh basil leaves before serving.
Notes
Let the dish sit for a few minutes before serving for easier slicing.