In a bowl, mix together all the ingredients given under "for marinade" and add the chicken thighs to it. Cover the bowl using a tight lid or cling film and leave it aside to marinate until the curry is done.
Place clean and dry inner vessel into the Instant Pot. Set it to SAUTE mode for 20 minutes. Add the butter and wait for it to just melt.
Add the chopped onions and saute it until translucent. Then, add the ginger garlic paste and sauté for a minute.
Quickly pour in the tomato puree and add the tomato paste. Pour the water into the Instant Pot and switch the Instant Pot OFF.
Add the spice powders: Kashmiri Chilli Powder, Coriander Seed Powder, Turmeric Powder, Garam Masala Powder, Cumin seed powder; and the salt. Mix everything and cover with the lid.
Place a grill pan on the stove and apply some vegetable oil on it. Once the grill pan is hot, place the marinated chicken pieces on it. Cook on high heat for just a a few minutes; only until it chars at a few places and is cooked on the outside. The chicken pieces doesn't have to cook through, we just want to lock the flavors in.
Once done, add it to the curry base in the instant pot. Cover and SEAL with its lid. Set it to PRESSURE COOK mode for 10 minutes.
After the timer goes off, Quick Release and carefully open the lid when the safety button is down.
Add the cream and butter to the curry. Stir and bring it to a boil in SAUTE mode. Switch OFF the Instant Pot and check seasonings.
Serve it with freshly made rotis or laccha parathas or any flat bread you like!