Add 1 cup water to the base of the instant pot insert.
Then add the chicken, pizza sauce and pepperonis over top of the chicken and sauce.
Set on Manual, High for 15 minutes.
If cooking from frozen, set on Manual, High for 22 minutes, or until chicken is cooked through.
Quick release the vent and then check to make sure it's done. If it's not done, run it for another 2-3 minutes.
Keep it on warm mode, add the shredded mozzarella cheese right onto each piece of chicken and let melt while on warm mode.
Use a slotted spoon to remove the chicken and drain the juices from the slow cooker. Garnish with grated Parmesan cheese.
Cook the pasta as directed.
Serve Instant Pot Pepperoni Chicken over pasta rice with veggies.