In a mixing bowl, combine ricotta, half the mozzarella, parmesan, garlic, egg, half of the salt and pepper. Transfer mixture to a pastry bag, or gallon size plastic bag and snip the corner.
Boil the pasta shells until al dente, 8-10 minutes, then run under cold water to stop the cooking, and drain well.
Spray the inside of the Instant Pot with cooking spray and place the trivet in the bottom of the Instant Pot.
Fill each pasta shell with filling, about a tablespoon per shell then stack the shells on the trivet in the Instant Pot.
Pour water down the side of the Instant Pot so it fills up under the shells (ie don’t pour the water directly onto the shells).
Pour the marinara sauce over the top of the shells. Sprinkle it with remaining salt and pepper. Do not stir.
Close the lid and turn the valve to sealing, if necessary. Press the Pressure Cook or manual button and set to cook for 10 minutes on high pressure. When done, do a quick pressure release.
Top with remaining mozzarella cheese. Set the lid back on the pot for about 3 minutes, until the cheese has melted. Serve with a sprinkle of parsley and/or Parmesan cheese, as desired. Serve straight from the Instant Pot or remove the shells from the pot. There will be more sauce under the trivet.
Note: We are cooking the shells on the trivet because the shells can burn being placed right into the bottom of the Instant Pot.
NOTES
Cooking the pasta directly in the Instant Pot may lead to a burn notice and burnt pasta. We are cooking the shells on the trivet to avoid that issue.
