1. Mix the yogurt, chicken and tikka spice in a bowl and let sit in the fridge. You can do this overnight but if you’re doing it day-of, give it at least 20 minutes to marinate.
2. Heat a pan on medium high heat and add 1 tablespoon of butter or cooking oil to the pan. Sautee marinated chicken pieces until browned. Chicken should be almost cooked through. Takes about 5 minutes depending on the size of the pieces.
3. Set chicken aside and return the pan to medium heat
4. Melt butter in pan in the same pan and add the chopped onion.
5. Cook onions until soft but not browned.
6. Add tomato paste and stir into onions. Let this cook for a minute or two then add the tikka spice and sautee for an additional minute until the spices are fragrant.
7. Add the crushed tomatoes and reduce the heat to medium-low.
8. Add the chicken to the sauce and continue to simmer for 10-15 minutes. You may need to reduce the heat to achieve a slow simmer.
9. Reduce heat to low and add the cream, stirring to incorporate and simmer for an additional 5 minutes
10. Serve with a garnish of chopped cilantro and enjoy.

Congratulations, you are awesome and have just made restaurant-style tikka masala from scratch!