Cook pasta shells according to directions until they are al dente. Do not overcook. Run under cold water as soon as they are removed from the boiling water. Set aside for now.
Preheat the oven to 350 degrees Fahrenheit and spray a 9x13 baking pan with cooking spray.
Mix the ricotta cheese, egg, lemon juice, salt, garlic powder, onion powder, dried basil, dried oregano, and black pepper in a small bowl.
Pour and spread 1 ¾ cup of the marinara sauce into the bottom of the dish.
Fill each pasta shell with the ricotta cheese mixture and place them evenly throughout the baking pan.
Once all pasta shells are filled and nestled into the sauce, drizzle the remaining marinara over all the shells and top off with mozzarella cheese.
Bake in the oven for 20-25 minutes or until the sauce is bubbly and the cheese is melted.
Broil for 2 minutes to get your cheese nice and toasty (if you prefer). Serve garnished with minced fresh parsley, if desired.