Boil water in a large pot. Add manicotti shells and cook until slightly tender. Do not overcook them. Drain carefully and let them cool before handling.

In a bowl, mix ricotta cheese, half mozzarella, Parmesan, egg, garlic, parsley, salt, pepper and Italian seasoning. Stir until smooth, creamy and well combined.

Preheat your oven to 180°C (350°F). This helps the pasta bake evenly and melt the cheese perfectly. Lightly grease a baking dish with olive oil.

Take each cooked pasta shell. Carefully fill it with the cheese mixture using a spoon. Fill evenly but do not overstuff to avoid breaking.

Spread a layer of marinara sauce at the bottom of the baking dish. This prevents sticking and adds flavor to the pasta while baking.

Place the filled manicotti shells in the baking dish. Keep them in a single layer. Make sure they are close but not overcrowded.

Pour the remaining marinara sauce over the pasta. Sprinkle the remaining mozzarella cheese evenly on top for a cheesy baked finish.

Cover the dish with foil and bake for 25 minutes. Remove foil and bake for another 15 minutes until cheese melts and becomes golden and bubbly.