Rub the chicken and tomato halves with the yoghurt, salt, pepper, lemon juice and garam masala - keep this aside
In a blender/mixer make a smooth paste out of the basil leaves, pine nuts (or walnuts), olive oil, garlic, chilis and cheese. This is the pesto sauce
Add the sauce to the chicken and tomatoes and massage well. Cover with a cling film or lid and leave it in the refrigerator for at least an hour
Thread your skewers with the chicken and tomatoes. About 5-6 pieces of chicken per skewer works well, keep them closely packed
Grill in a pre-heated oven, at 180°C, for 20-30 minutes or until the chicken is fully cooked. If cooking on a grill plate, grease it with olive oil and place the skewers on it. Keep turning and cooking them until fully done
Once done remove from the oven (or grill plate), drizzle chaat masala on them and serve your delicious spicy pesto chicken kebabs with a cooling mint-coriander chutney. Enjoy!