Season the chicken with garam masala, cumin, paprika, turmeric, cayenne (if using), and salt. Toss to coat evenly and set aside.

Set the Instant Pot to 'Sauté' mode and heat the vegetable oil. Add the onion, garlic, and ginger, sautéing until the onion is translucent and the mixture is fragrant, about 3 minutes.

Add the seasoned chicken to the pot and sauté until the chicken is browned on all sides, approximately 5 minutes.

Pour in the tomato sauce and stir to combine. Secure the Instant Pot lid and set the valve to 'Sealing'.

Select the 'Manual' or 'Pressure Cook' setting and adjust the time to 10 minutes on high pressure.

When the cooking cycle is complete, carefully perform a quick release by moving the valve to 'Venting'.

Remove the lid and select 'Sauté' mode again. Stir in the heavy cream and let the sauce simmer for 5 minutes until it thickens slightly.

Turn off the Instant Pot and let the Chicken Tikka Masala rest for a couple of minutes before serving.

Garnish with fresh cilantro and serve over cooked rice or with warm naan bread.