1. Preheat the oven to 375˚F
2. Then start by cooking the pasta shells in salted water for half the cooking time stated on the pasta package, drain them from the hot water and dunk them inside a bowl filled with cold water or just fill the pot with cold water after draining the hot one, this would prevent sticky pasta shells.
3. Next make the sauce, in a deep pan placed over medium-high heat add 2 tablespoons of olive oil and chopped onion, cook, and stir for about 3-5 minutes till it starts to get softer and a little golden.
4. Add some minced garlic, ½ teaspoon salt, ¼ teaspoon oregano, and black pepper and saute for a minute, stir this mix until you start to smell it.
5. Add 3 cups of marinara sauce and continue boiling for about 2-3 minutes, once ready remove from heat and pour it inside the casserole dish you’ll be using.
6. Next, make the filling, add 2 cups of mozzarella, 16 oz ricotta, and ⅓ cup parmesan cheese with 1 raw egg, ½ teaspoon salt, ¼ teaspoon black pepper, and ¼ cup of parsley. Stir this mixture thoroughly until they are properly combined.
7. Use a piping bag or a small spoon to fill the shells, after stuffing them place them properly in the casserole dish on top of the marinara sauce. As a finishing touch before baking, sprinkle some mozzarella cheese on top and maybe some sauce too.
8. Cover the casserole dish with a foil and bake for 30 minutes, after that remove the foil and broil for about 2-4 minutes to get that nice brown color and crust. Once it’s ready, remove it and sprinkle some chopped parsley or basil on top and serve.

If you’d still like more ideas and inspirations for making stuffed shells, then check out this video recipe