2 Dried Ancho Chiles, or 3 teaspoons powder
1 (28-oz.) Canned Unsalted Whole Tomatoes
1-2 cups chopped Yellow Onion
1/2 cup toasted Sliced Almonds
3 ounces Dark or Semi-Sweet Baking Chocolate, finely chopped (about 1/2 cup)
1/4 cup Unsalted Chicken Stock
1 tablespoon Ground Cumin
2 tablespoons Canned Adobo Sauce
1 teaspoon ground Cinnamon
1/4 teaspoon Cardamom
3 Chipotle Chiles, canned in adobo sauce
4 Garlic Cloves, smashed
2 pounds Chicken Breasts
1 teaspoon kosher Salt
16 (6-in.) Corn Tortillas
1 ounce Cotija Cheese, crumbled (about 1/4 cup)
1/4 cup fresh Cilantro, leaves
2 Limes, cut into wedges
Place ancho chiles in a bowl; cover with water. Let stand 10 minutes. Drain; remove and discard stems and seeds. Process seeded chiles, tomatoes, onion, almonds, chocolate, stock, cumin, sauce, cinnamon, chipotle chiles, and garlic in a food processor until smooth.
Sprinkle chicken with salt; place in a 6-quart slow cooker. Add tomato mixture. Cover and cook on low 8 hours. Place chicken on a cutting board; remove bones. Reserve 2 cups sauce for another use. Shred chicken into large pieces; return to slow cooker. Add salt to taste.
Working with 1 tortilla at a time, heat tortillas over medium-high directly on burner until lightly charred, about 15 seconds per side. Top tortillas with chicken mixture, cheese, and cilantro. Serve with lime wedges.