In a separate bowl, mix together the yogurt, ginger-garlic paste, garam masala, cumin, coriander, chili powder (if using), turmeric powder and lemon juice.
Add the yogurt mixture to the chicken and mix until all the pieces are evenly coated.
Cover and refrigerate for at least 2 hours or overnight.
Preheat the oven to 400°F (200°C).
Thread the chicken cubes onto skewers and place on a greased baking sheet.