Shred cooked chicken (cut against the grain), and mix with cayenne pepper, 1 tsp garam masala, paprika, and 1/4 cup chicken broth. Marinate for at least 1/2 hour.
Melt butter in large frying pan. Stir in garlic and ginger, stirring until moisture is evaporated. Add onions and fry for 1 minute. Add 1 tsp garam masala, and stir for several minutes. Add tomatoes, salt, pepper, onion powder, and curry paste.
Stir for 5 minutes, then add yogurt and chicken. Simmer for another 10 minutes, at least.