From Ancho seasoning to mole: In a medium-size (4-quart) pot (preferably a Dutch oven or Mexican cazuela), heat 1 1/2 tablespoons of the oil or lard over medium. Add the almonds and cook, stirring regularly, until lightly toasted, about 3 minutes. Using a slotted spoon, remove the almonds to a blender or food processor. Add half of the onion to the pan and cook, stirring frequently, until richly browned, about 10 minutes. Use the slotted spoon to scoop the onions in with the almonds, leaving behind as much oil as possible. (If needed, add a little more oil or lard to the pan, let heat, then continue.) Add the raisins, stir for a minute as they puff, then use the slotted spoon to scoop them in with the almonds.
Roast the tomatoes on a baking sheet 4 inches below a very hot broiler until blackened on one side, about 6 minutes, then flip them over and roast the other side. Cool, peel and add to the almond mixture in the blender, along with the cinnamon, chocolate and bread. Add 1 cup of the broth and blend to a smooth puree, scraping and stirring every few seconds.Return the pot to medium-high heat and, if necessary, add a little more oil or lard to coat the bottom lightly. When very hot, add the Ancho mixture and cook, stirring almost constantly, until darker and very thick, about 5 minutes. Add the pureed almond mixture and cook, stirring constantly for another few minutes, until very thick once again. Stir in the remaining 4 1/3 cups of the broth, partially cover and simmer, stirring occasionally, over medium-low for 45 minutes. Taste and season with salt and sugar. (If you have never made mole before, season it until it's slightly sweet--the sugar balances the strong flavors.)
Warming the tortillas: Set up a steamer (with this many tortillas, you'll need 2 vegetable steamers set up in saucepans or a big Chinese steamer--either choice with 1/2-inch of water under the steamer basket); heat to a boil. Wrap the tortillas in 2 stacks in heavy kitchen towels, lay in the steamer, and cover tightly. Boil 1 minute, turn off the heat and let stand without opening the steamer for 15 minutes.
Finishing the enchiladas: Turn on the oven to the lowest setting and warm 6 to 9 plates in it. Toast the sesame seeds in a small skillet, stirring frequently, over medium heat until golden, 2 to 3 minutes. In a medium-size saucepan, combine the chicken with 1 1/2 cups of the mole and warm over medium heat. Bring the remaining mole to a simmer.
When you're ready to serve, quickly make the enchiladas by scooping 2 generous tablespoons of chicken onto a tortilla, rolling it up and placing it on a warm dinner plate. Continue making enchiladas, arranging 2 or 3 per plate, then douse them liberally with the hot mole. Strew with the remaining sliced onion and sesame seeds.