Warm a skillet to medium heat. Cook and crumble Italian sausage until cooked through. Add chopped spinach and cook for an additional 1-2 minutes or until spinach is wilted.
Meanwhile, cook pasta shells according to box directions.
In a separate bowl mix together ricotta, mozzarella, parmesan egg, garlic powder, and oregano. Mix together well then add cooked ground sausage and spinach and mix again.
Preheat the oven to 350 degrees. Fill the bottom of a casserole dish with the entire jar of marinara and set aside.
Drain pasta and fill each jumbo shell with ricotta mixture. Place each stuffed shell in the bottom of your prepared casserole dish.
Bake for 20-25 minutes. Serve and enjoy!