Marinade the chicken overnight or for at least 1 hour.
Sear the chicken in a little oil and butter.
Remove the chicken from the pan and add the diced onions, garlic paste, and ginger paste. Cook for a few minutes.
Add the canned tomatoes and soaked cashews. Simmer for a few minutes and then blend until smooth.
Pour the blended sauce back into the pan and add the spices (garam masala, cumin, chili powder, turmeric, salt, sugar, fenugreek).
Add the chicken back to the pan and simmer for 5 minutes to finish cooking the gravy.
Drizzle cream and sprinkle cilantro for garnish.
Serve with garlic naan and basmati rice.