Add oil to the insert of a 6 or 8 quart Instant Pot. Press the saute function, and heat the oil. Once hot, add garlic and ginger and cook while stirring, until fragrant, about 1 minute.: You should hear an immediate gentle sizzle and smell a burst of sharp, aromatic heat from the garlic and ginger as they hit the pan. Visually, the minced garlic will begin to glisten and the grated ginger will look slightly translucent, releasing bright steam. This step wakes up the spices and creates a fragrant base that carries through the whole dish. Cook only until fragrant, because overcooking will lead to bitterness. If you notice browning too fast, lower the heat or remove the insert briefly to cool, as burnt aromatics are hard to mask later.
Add tomato paste, tomato puree, garam masala, turmeric, salt and cumin and cook for 3 minutes, stirring occasionally. Shut off the saute function and add in cinnamon stick, chicken stock and stir together. Place the chicken breasts inside.: Right away the tomato paste will darken and take on a concentrated, caramelized scent, while the puree loosens into a cohesive sauce. Stirring coaxes the spices into the oil so they bloom, releasing warm, earthy aromas from the garam masala and turmeric . After about three minutes the mixture should smell round and slightly sweet, not raw. Shutting off sauté before adding the liquid prevents splatter and sudden temperature shocks. When you add the chicken stock and place the chicken , you ll see the sauce thin slightly and steam begin to rise, signaling everything is ready for pressure cooking. Avoid crowding the pot, as cramped chicken can cook unevenly.
Arrange a 2.5-inch trivet over the chicken and place a 7-inch oven-safe bowl on top. Add the rice and water to the bowl. Secure the lid and move the steam release valve to Sealing. Cook on manual high pressure for 12 minutes. Move the steam release valve to venting to quickly release the steam pressure. When the floating valve drops, remove the lid.: When you set the trivet and bowl, you re creating a gentle steam environment so the rice cooks separately from the sauce, while still absorbing subtle savory steam notes. As pressure builds you might hear soft clicks and a higher pitched hum, which is normal. The 12 minute high pressure time yields tender chicken and fluffy rice ; the quick pressure release prevents overcooking the rice. Be cautious when turning the valve to venting because a rush of hot steam will escape rapidly. Use an oven mitt or long utensil to protect your hand. If the pot sputters a lot during venting, it may be because the bowl was too full; next time leave a little headspace.
Remove the rice and the trivet. Fluff the rice, cover to keep warm and set aside. Remove the chicken and dice into bite-sized pieces and set aside.: The rice should look glossy and the grains separated, and when you fluff it with a fork you ll see steam rise and smell a faint savory sweetness from the pot below. Keeping it covered holds that steam and texture. The chicken will be tender and should pull apart easily when diced; its surface will be coated lightly with sauce. If you find the chicken still firm in the center, return it briefly to sauté mode with a splash of stock to finish gently. Avoid over chopping the meat too finely, as that can make the bites dry.
Press the saute function and whisk in the butter and cream and cook until slightly thickened, about 2 minutes. Add the diced chicken back to the pot to heat through.: As you whisk in the butter and cashew cream , watch the sauce shine and coat the whisk; it should thicken to a ribbon like consistency that clings to the spoon. You will smell a rich, buttery perfume that mellows the tomato brightness and deepens the sauce s body. Reintroducing the diced chicken warms the pieces and allows the sauce to fully coat every bite. Keep the sauté on medium to prevent the dairy from separating. If the sauce looks curdled, lower the heat and stir gently, adding a tablespoon of stock to smooth it back out.
Serve the chicken with the rice, and garnish with cilantro, if desired.: The final bowl should present glossy, warmly colored sauce pooled around tender chunks of chicken with fluffy white rice alongside. Add a scatter of fresh, bright cilantro for a contrasting aroma and fresh snap. Taste for final seasoning and adjust with a pinch of salt if needed before plating. The ideal mouthfeel balances creamy sauce with tender protein and light, airy rice. Avoid letting the dish sit too long before serving, as the rice can become gummy and the sauce will cool and lose its silkiness.