Preheat oven to 350 degrees F.
Heat oil in a saute pan over medium heat. Add onion and saute until translucent. Add garlic and spices and continue to saute to toast and develop flavor. Add diced tomatoes, peppers, chipotles, broth, peanut butter, and chocolate. Simmer for 10 minutes. Strain and puree until smooth.
Sear the 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 the oven for 45 minutes to 1 hour. Garnish with pepitas and serve with white rice.