NOTE: for the tomatoes, drain them lightly and don't drain them completely dry, or you may have to supplement the sauce with jarred salsa (see sauce preparation instructions below).
NOTE: for the chicken, I usually season 3 skinless boneless breast halves with Tone's Lime Pepper seasoning or Goya Adobo con Pimiento, then toss them on the Foreman grill for about 8 minutes.
TO PREPARE THE TORTILLA CHIPS:
Preheat oven to 375°F.
Stack tortillas into three piles of four tortillas each. Cut each pile like a pie into 8 sections.
Spray 2 large baking sheets with cooking spray. Divide the tortilla chips between the two pans, keeping them in as much of a single layer as possible.
Mist the chips with cooking spray, and bake them (stirring them a bit, once or twice) for 10 to 15 minutes, or until crispy and golden.
Sprinkle with salt, if desired.
TO PREPARE THE SAUCE:
Pour the drained tomatoes and the chipotles (seeds and all) into a blender. Coarsely puree the mixture (it shouldn't be totally smooth).
You need to have approximately 2 1/4 cups of puree. If you come up short, rather than using another partial can of tomatoes, you can supplement the mixture with some jarred salsa (I use taqueria salsa from either Goya or La Victoria).
In a large Dutch oven with a lid, heat the vegetable oil and cook about 1/2 cup of the onion, stirring regularly, for about 7 minutes or until golden.
Add the garlic and cook for another minute, stirring so garlic doesn't burn.
Increase heat to medium-high and add tomato/chipotle puree. Stir almost constantly until the mixture thickens up a bit, about 4 or 5 minutes.
Stir in the broth, and salt to taste (keeping in mind the salt that will be added from the chips, if you used it).
FINAL COOKING AND ASSEMBLY:
Bring the sauce to a boil over medium-high heat. Add the chips and stir to coat.
Bring sauce and chips to a rolling boil again. Cover the pan, turn off the heat and allow to stand for 5 minutes (no longer, because the chips should be s bit chewy and not mushy). Sprinkle cilantro into the pot.
Dish out mixture onto 4 warm plates. Divide chicken evenly over top of tortilla mixture and stir lightly to coat chicken with sauce. Top with crema or thinned sour cream, remaining chopped onions and both cheeses, then serve.