In a bowl, toss the cubed chicken with yogurt and half of the garam masala (1/2 tbsp). Let marinate for 10 minutes.
Heat olive oil in a large skillet over medium heat. Add the marinated chicken and cook for 5-7 minutes until browned. Remove chicken and set aside.
In the same skillet, add the diced onion, cooking for 5 minutes until soft. Stir in garlic and ginger, cooking for 1 minute until fragrant.
Stir in the remaining 1/2 tbsp garam masala, turmeric, cumin, and crushed tomatoes. Simmer for 10 minutes.
Stir the chicken back into the skillet along with the coconut milk. Simmer for another 5 minutes until the chicken is cooked through and reaches an internal temperature of 165°F.
Garnish with chopped cilantro and serve warm with steamed white rice or gluten-free naan.