Cut the chicken thighs into bite-sized pieces and season with salt and half of the garam masala.
Melt 1 tablespoon of butter in a large skillet over medium-high heat and brown the chicken pieces. Remove and set aside.
In the same skillet, melt the remaining butter. Add the chopped onion, cooking until translucent.
Stir in the minced garlic and grated ginger, cooking for 1 minute until fragrant.
Add the remaining garam masala, cumin, and chili powder, stirring constantly.
Pour in the tomato puree and simmer the sauce for 10-15 minutes until it thickens.
Return the chicken to the skillet, stir in the heavy cream, and simmer for another 5 minutes until the chicken is cooked through.
Garnish with fresh chopped cilantro and serve hot over basmati rice.