Soak the pasilla and ancho peppers in warm water for 30 to 60 minutes then remove the stems and seeds.
Place the chicken pieces in a braiser and cover halfway with stock, using about 2 cups. Lightly salt the chicken pieces, cover the pot and cook on medium-high heat until the chicken is almost cooked through—about 20 minutes. Drain the stock and reserve it.
Pat the chicken dry—taking off as much moisture as possible from the skin.
Heat the lard in a sauté pan and brown the chicken pieces. Place the browned chicken back into the pot and keep warm, off of the heat.
In a second sauté pan, toast the almonds and sesame seeds then combine in a blender or food processer with the peanut butter, onion, garlic, tortilla, spices, raisins, tomatoes and pasilla, ancho, and chipotle chilies, pulsing to a puree.
Heat the vegetable oil in the same pan used to brown the chicken, then add the puree and cook over medium-high heat for about 5 minutes—stirring constantly. Add the reserved chicken stock, Nutella and salt and simmer until all the ingredients are well combined—about 5 minutes.
Pour the sauce over the chicken pieces in the large pot, cover and cook at a simmer for another 45 minutes—stirring occasionally. A nice nappe consistency is desired (the sauce should coat the back of a spoon)—if the sauce is too thick, add a little water or canned stock.