In a food processor, chop the whole tomatoes to your desired thickness.
Pour half of the tomato sauce into the pressure cooker.
In a large bowl, combine the Ricotta Cheese, 1/2 of bag of Mozzeralla Cheese, Basil, Italian Seasoning and Salt & Pepper and mix well.
Place a slice of Pepperoni into the bottom of each shell.
Using a spoon, fill the cheese mixture into each shell evenly and place into the pressure cooker.
Add the remainder of the tomato sauce onto the shells in the pressure cooker.
Add in the chopped garlic.
Add in 1/2 cup of water to the pressure cooker around the shells.
Set your pressure cooker to high and cook for 10 minutes.