Set the pot to Sauté setting. Add the meat and onion. Cook, stirring occasionally, until meat is no longer pink.

Add the Italian seasoning, garlic powder, salt, and pepper. Stir.

Pour in the chicken broth and stir.

Pour in the pasta shells and spread in an even layer. Press them down into the liquid with a spoon, but do not stir.

Pour the jar of marinara over the pasta and cover it completely. Again, do not stir.

Put the lid on and set the steam release knob to the Sealing position. Cancel the Sauté setting.

Press the Pressure Cook/Manual button or dial and then the + or - button or dial to select 5 minutes. The pot will take a few minutes to come to pressure.

When the cooking cycle is finished, let the pot sit undisturbed for 3 minutes (3 minute natural release). If you like a firmer al dente pasta, don't do this step. Do a controlled Quick Release instead. See next step.

Manually release the remaining steam/pressure by turning the steam release knob to the venting position, or pushing button, if applicable. Do this in short bursts at first so you don't get sauce spewing out with the steam, due to the force. Once you are sure you will only have steam coming out, you can open the vent fully and let it go. This is called a Controlled Quick Release.

Remove the lid and stir the contents. Add the parmesan cheese and stir. Then add the mozzarella and stir.

Serve hot, with some crusty bread.