Cut the chicken pieces neatly into quarters.

Put tomatoes, jalapeno and ginger in a blender or food processor and blend to a fine puree.

Place 1 stick of butter in a large, heavy-bottomed pan over medium heat. When the foam begins to subside, add the chicken pieces, a few at a time, and sear until they are nicely browned all over (about 2-3 minutes per batch). Remove them with a slotted spoon into a bowl and put aside.

Add the 4 teaspoons of cumin and the paprika to the butter in the pan and cook, stirring rapidly, for 10-15 seconds. Add the tomato mixture and cook, uncovered, until the sauce is thickened (about 5-8 minutes), stirring constantly to prevent sticking and burning.

Add salt, cream, yogurt and chicken pieces (with any juices that have accumulated in the bowl) to the pan. Gently stir the chicken to coat the pieces evenly and thoroughly with the sauce. Be careful not to break the fragile chicken pieces. Reduce heat to medium-low and simmer, uncovered, until the fat begins to separate from the sauce and a thin glaze appears on the surface (about 10 minutes). Check and stir often (but only one or two stirs at a time) to ensure that the sauce is not burning.

Stir in the remaining 2 tablespoons (1/4 stick) of butter, garam masala, and roasted cumin.