Add 6 oz of pasta sauce to the bottom of pressure cooker and add water.
In a bowl, combine, ricotta, spinach, garlic, Parmesan, salt, and pepper. Spoon this cheese mixture into shells and place them into the pot. Cover shells with the rest of the pasta sauce.
Close and lock the lid and set to multi grain for 10 minutes.
When done, quick release and make sure all pressure is released before opening lid.
Carefully open lid and top with mozzarella cheese and let it melt. Serve and enjoy.