Cut the chicken in half horizontally. Combine the chicken, yogurt, and 1/2 teaspoon garam masala. Place on a foil lined baking sheet coated with cooking spray; sprinkle with 1/8 teaspoon salt. Broil 5 minutes on each side.
Heat a skillet over medium-high heat. Place the tomatoes in a mini chopper/processor; pulse until almost smooth. Add oil to the pan. Add 1 1/2 teaspoons garam masala, ginger, red pepper, and garlic; cook 1 minute. Stir in tomatoes; simmer 4 minutes. Stir in 1/2 teaspoon salt and cream; cook 1 minute. Cut chicken into bite-size pieces. Add chicken to the pan and toss.
Place the pitas on a baking sheet. Broil one minute on each side.
Spoon 1/2 cup chicken onto each. Top with onion and cheese. Broil 2 minutes. Sprinkle with cilantro.