Method:
Place chicken, 2 1/2 cups broth and salt in a large pot; bring to a boil. Reduce heat to medium-low and simmer 25 minutes, turning chicken over halfway through cooking.
Meanwhile, heat a large skillet over medium heat until hot. Add pepitas, sesame seeds, cinnamon and red pepper flakes to the skillet and toast, stirring frequently, about 5 minutes or until fragrant. Remove from heat and place in a blender. Pulse until mixture resembles a powder. In the same skillet, toast guajillo chile until fragrant, about 30 seconds. Add remaining broth, tomatoes and tomatillos and bring to a boil. Reduce heat to medium and simmer until tender, about 10 minutes. Remove from heat and add to the blender with spice mixture. Tear 2 tortillas into large pieces, add to the blender with spices and tomato mixture and purée, taking care as the mixture is hot.
Pour purée into the pot with chicken, stir and continue to simmer 10 minutes or until chicken is cooked through and sauce is hot.
Warm remaining tortillas and serve with chicken, sauce and rice.