For the chicken broth: Rinse the chicken and pat dry. Place all 8 pieces of chicken in a large heavy pot with 8 cups boiling water. Add the garlic, onion and salt. Bring to a boil again. Reduce to a simmer and cover. Cook for about 1 hour. Remove the chicken and set aside. Maintain a medium heat under the broth as you'll use it again for this recipe.
For the roasted vegetables: Preheat the oven to 400 degrees F. Place the tomatoes, onion and garlic onto a parchment-lined baking sheet. Drizzle lightly with olive oil and roast until the skins are blistered and the vegetables softened, 30 to 40 minutes. Remove from the oven to cool. Once cooled, remove the foil and peel the garlic and the skins off the tomatoes.
For the mole: In a large heavy saute pan heat 1 cup lard. Quick fry the chiles in the hot lard, being careful not to burn them or they'll become bitter. Add the chiles into the pot of chicken broth and simmer for 10 minutes.
In the meantime, add 2 tablespoons lard to the saute pan and fry the roasted onions and garlic. Add the tortilla and bolillo and cook for 5 minutes. Add the peanuts, pumpkin seeds, sesame seeds, blanched almonds, raisins, oregano, cumin, thyme, coriander seeds, whole black peppercorns and cinnamon stick. Saute for 4 minutes and remove from the heat. Cool slightly. Remove the cinnamon stick and discard.
Working in two batches, transfer half of the cooled nut and seed mixture into a large-capacity blender. Then transfer half of the simmered chiles, without the broth, into the blender. Add half of the roasted tomatoes and fresh tomatillos. Allow to cool before blending. Process until smooth. A paste will form. If the mixture is too dry, add 1 cup of reserved chicken broth at a time. Strain the mixture into a large mixing bowl. Then repeat with the remaining ingredients, processing until smooth and then strain.
Clean the saute pan and place over medium-high heat. Add the remaining 2 tablespoons lard. Pour in the strained mole sauce and cook for 2 minutes. Season with the salt, some pepper and the sugar. Add 1 1/2 cups of the reserved chicken broth and stir to combine. Add the Mexican chocolate and stir to melt. Simmer for 15 minutes, uncovered. Return the chicken to the saucepan with the mole and cook until the chicken is warmed through, an additional 5 minutes. Remove from the heat and transfer to a large serving bowl or platter. Sprinkle with some sesame seeds and a couple pinches of sugar if desired. Drizzle the Mexican crema over the chicken mole and serve hot.
When blending hot liquid, first let it cool for five minutes or so, then transfer it to a blender, filling only halfway. Put the lid on, leaving one corner open. Cover the lid with a kitchen towel to catch splatters, and pulse until smooth.