Heat a large skillet over medium heat and add a splash of olive oil. Sauté minced garlic until fragrant, about 1 minute. Add ground beef or sausage and cook until browned, approximately 5-7 minutes. Stir in marinara sauce and sprinkle with Italian seasoning. Let simmer on low for 20 minutes.

In a large pot of boiling, salted water, gently add the manicotti shells. Cook until al dente, about 6-8 minutes, then drain and rinse under cold water. Set aside on paper towel to cool slightly.

In a mixing bowl, combine ricotta cheese, shredded mozzarella, and grated Parmesan. Blend until smooth, adding a splash of milk if needed.

Using a pastry bag or spoon, stuff each manicotti shell with the cheese mixture. Arrange them in a single layer in your baking dish.

Spread a thin layer of meat sauce at the bottom of the baking dish. Place the stuffed shells on top, then cover generously with remaining meat sauce. Top with remaining mozzarella and Parmesan.

Cover tightly with aluminum foil and preheat the oven to 350°F (175°C). Bake for 30 minutes, then remove the foil and bake for an additional 10 minutes.

Let rest for 5-10 minutes before slicing. Serve hot, garnished with fresh basil or parsley.