Bring a pot of salted water to a rolling boil and cook the jumbo pasta shells according to the package instructions until al dente. Drain and set aside to cool slightly.

In a mixing bowl, combine the ricotta cheese, half of the shredded mozzarella, salt, pepper, and Italian seasoning. Mix well until fully incorporated.

Take a spoonful of the ricotta mixture and stuff each pasta shell generously. Place the stuffed shells in the bottom of the slow cooker.

In a skillet over medium heat, cook the ground beef until browned. Drain any excess fat, then pour in the marinara sauce. Stir well until the beef is evenly coated in the sauce.

Pour the beef and marinara mixture over the stuffed shells in the slow cooker.

Cover the slow cooker with the lid and set it to low for 4 hours or high for about 2 hours.

When there are about 30 minutes left, sprinkle the remaining mozzarella over the top and let it melt.

Once done, take it out and let it cool for a few minutes. Garnish with fresh herbs or Parmesan cheese if desired.