Set to saute and sear the chicken in pot, set aside.
Add the garlic, onion, bell peppers, carrots, to the pan and saute 4-5 minutes, add mushrooms, and saute another 2-3 minutes.
Add diced tomatoes, and scrape bottom of pot, add tomato paste, fresh thyme, dried basil, oregano, red pepper flakes, rosemary, thyme, salt, and pepper to taste into the Instant Pot.
Place chicken in the Instant Pot.
Add spaghetti squash halves cut side down on top of chicken mixture.
Cover and close vent. Set to High Pressure, 25 minutes. Vent.