Preheat oven to 350.
Heat oil in saute pan over medium heat.
Add onion and saute until translucent.
Add garlic and spices. Continue to saute to toast and develop flavor.
Add diced tomatoes, peppers, chipotles, broth, peanit butter, and chocolate.
Simmer for 10 minutes. Strain and puree until smooth.
Sear chicken in a heavy bottomed hot saute pan over medium-high heat until browned on both sides.
Add to casserole dish, cover with sauce and braise in the oven for 45 minutes to 1 hour.