In a medium bowl, combine chicken, tbsp. curry powder, turmeric, all-spice, cayenne pepper and salt. Add ginger, garlic, onion, bell pepper, cilantro and thyme sprigs. Mix all ingredients together. Cover wit plastic wrap and let sit for 30 minutes.
In a large skillet, heat oil and butter over medium heat. Add tbsp. of curry powder, and stir until mixed. Add chicken mixture and sauté until browned, approximately 5 minutes.
Stir in chicken broth and coconut milk. Bring to a boil, then add potatoes and carrots. Cover and reduce heat to low. Simmer for 25 minutes, stirring occasionally. Sauce will thicken. Taste and add more salt if needed.
Serve immediately with white rice. Garnish with cilantro, optional.