Cook jumbo shells according to pasta instructions and set aside.
In a large skillet, add the oil and peppers and saute until soft. Then add sausage and beef and cook until cooked through.
Mix in the marinara sauce until smooth. Stir in garlic powder, onion powder, salt and pepper and set aside.
In a large bowl, combine ricotta, spinach, eggs, mozzarella, parmesan, garlic powder and salt. Mix well. Stuff the ricotta mixture into the shells until they are packed.
In a large 13-inch skillet, add two large spoonfuls of sauce to the bottom of the pan. Then, arrange the stuffed shells in a ring. Add the remaining sauce on top. Bake for 20 minutes, then fully cover with 2 cups mozzarella cheese and increase the oven temperature to 375°F. Bake for 15 minutes, or until the cheese is fully melted. For best results, broil at the end.
Notes
Storage: Store leftovers in a sealed container in the refrigerator for up to 3 days. Reheat in the oven at 350°F until warmed through.