Make sure your items are ready: onion and garlic chopped, cilantro cleaned and chopped, cheddar shredded, etc.
IF USING FRESH CHICKEN: IN an oven proof skillet, heat 1 TBSP canola oil. Sauté chicken for 8 -10 minutes, turning occasionally to brown all sides.
PUT skillet in oven; bake at 425 deg. F for 10 minutes or until done. Remove chicken from skillet; let stand 15 minutes. Remove meat from bones; shred. Discard bones.
IF USING LEFTOVER CHICKEN: Separate pieces of chicken, sauté briefly to add flavor (optional).
REMOVE skin from chorizo, sauté until brown, stirring occasionally.
CONTINUE - PUT cooked chicken and chorizo in a medium bowl. ADD 1 1/2 tablespoons chopped cilantro, corn, 1/3 cup cream cheese or yoghurt, red pepper, cummin, salt (carefully, some ingredients already have salt in them), black pepper to chicken; toss to combine.
RETURN empty skillet to medium-high heat. Add 1/2 cup onion; sauté 5 minutes, stirring occasionally. Add 3 garlic cloves; sauté 30 seconds, stirring constantly until onion is transparent or light gold, not browned. ADD onion mixture to chicken mixture; stir to combine.
PREPARE SALSA MIXTURE: in separate saucepan, combine remaining 1 1/2 cups onion, remaining 3 garlic cloves, 1 cup broth, salsa, 1/4 cup water, and jalapeño in a medium saucepan over medium-high heat; bring to a boil.
REDUCE heat, and simmer 15 minutes, stirring occasionally. Remove from heat - mixture should be fairly liquid. let stand 10 minutes. Carefully pour salsa mixture into a blender; add 2 tablespoons cilantro. Process until smooth.
CUT tortillas in quarters and toast to 'crispy' in toaster, oven (325º oven, middle rack for 10 - 15 mins, turn once), or skillet on stovetop.
LIGHTLY coat the bottom of the casserole with vegetable oil or cooking spray.
LAYER ingredients into baking dish (larger dish, fewer layers, we use a single layer of chicken, but your choice): salsa - 1/2 of tortilla quarters - chicken - other 1/2 of tortillas - salsa) then sprinkle shredded cheddar on top.
BAKE at 425º for 15 minutes or until bubbly and lightly browned. Garnish with remaining cilantro.