Preheat oven to 375°F.

In a large oven safe pan (I used a cast iron pan 12 inches wide, 2 1/2 inches deep), heat oil over medium high heat.

In the meantime, pat chicken thighs dry with a paper towel, and then season with salt, pepper, and chili powder on both sides.

Place the chicken thighs into the pan, cooking them until they are golden brown on both sides (about 5 minutes per side).

Remove from the pan and set aside. Drain oil, reserving 1 tablespoon in the pan.

Over medium low heat, add onion to the oil in the pan. Sauté until soft and translucent, about 3 to 4 minutes. Add garlic and cook 1 to 2 more minutes.

Add a tablespoon of butter to the pan, along with the rice. Stir to coat.

Add salt, cayenne pepper, chili powder, and mango. Stir in the chicken broth and coconut milk and turn heat to medium high.

Bring the liquid to a low boil for a few minutes, then add the chicken (skin side up) back into the pan, cover with a lid or aluminum foil, and carefully place in the center of the oven. 

Cook covered for 25 minutes, then uncover and cook for an additional 10 minutes.

When the rice is tender and the chicken is cooked through (internal temperature should be 165°F.), carefully remove the pan from the oven. 

Set the chicken thighs on a plate, and then stir the zest and juice of one lime into the rice. 

Place the chicken thighs on top of the rice and garnish with fresh cilantro, mango and lime slices. Serve immediately.