1/2 or 1 teaspoon crushed red pepper flakes, optional
1 pound penne or spaghetti
1 1/2 cups shredded mozzarella cheese
1/3 cup freshly grated Parmesan cheese
2 tablespoons chopped fresh parsley leaves
Season chicken with salt and pepper, to taste. Place chicken into your instant pot.
In a large bowl, combine crushed tomatoes, onion, carrot, celery, basil, oregano, parsley and red pepper flakes, if using. Stir into the instant pot and gently toss to combine. Seal the valve and set the Instant Pot to Manual/High Pressure for 10 minutes. Let the Instant Pot release naturally for 10 minutes, then release remaining pressure.
Remove chicken from the slow cooker and shred, using two forks.
In a large pot of boiling salted water, cook pasta according to package instructions; save 1/2 cup of pasta water. Drain well.
Stir pasta and chicken into the instant pot; top with cheeses and mix until melted. Add some of the pasta water if desired. Season with salt and pepper to taste.
Serve immediately, garnished with parsley, if desired.