Prep the chicken: Pat the chicken dry and season with 1/2 teaspoon salt. Cut into even pieces so they cook uniformly.
Sauté aromatics: Set the Instant Pot to Sauté (Normal).
Add butter/ghee. When melted, add onion and cook 3–4 minutes until softened. Stir in garlic and ginger; cook 30 seconds until fragrant.
Add tomato paste and cook 1 minute to caramelize.
Build the sauce: Stir in the premade tikka masala sauce and 1/2 cup water/broth to loosen. Scrape the bottom of the pot with a spatula to remove any browned bits (this helps prevent the Burn warning).
Add chicken: Add the chicken and stir to coat evenly in the sauce.
Pressure cook: Seal the lid. Cook on Manual/Pressure Cook, High Pressure, for 6 minutes (thighs) or 5 minutes (breasts).
Allow a 5-minute natural release, then quick release the remaining pressure.
Finish the curry: Switch back to Sauté (Low). Stir in heavy cream and garam masala. Simmer 2–3 minutes until the sauce is silky and slightly thickened.
Taste and add more salt if needed.
Serve: Garnish with cilantro. Serve hot over basmati rice or with naan.