1. Heat broiler to high. Line broiler pan with nonstick foil.
2. In a small bowl, combine ginger, garam masala, garlic, salt and cayenne. In a large bowl, combine 1 tbsp of the ginger mixture and 1/2 cup of the yogurt. Add chicken and toss to coat. Place on prepared broiler pan and broil 6 inches from heat source for 6 minutes per side.
3. Meanwhile, heat oil in a large nonstick skillet over medium-high heat. Add onion and cook 5 minutes; stir in remaining ginger mixture and cook 1 minute. Stir in tomatoes, cream and remaining 1/2 cup yogurt. Simmer, covered, for 10 minutes, breaking up tomatoes with a wooden spoon. Add chicken to skillet; simmer, covered with lid slightly ajar, for 6 to 8 minutes or until internal temperature reaches 165 degrees .
4. Garnish with cilantro. Serve with rice and, if desired, naan.