Preheat oven to 425 deg f. Stack and cut the corn tortillas into quarters. Place on baking sheet and lightly coat with cooking spray. Sprinkle with salt and bake until crisp, about 8 minutes.
As tortillas cook, dice onion/jalapeno/chipotle and mince garlic. Reserve a bit of onion for garnish, and with a bit of saute oil over medium heat, cook onion, jalapeno, chipotle, tomato paste, garlic, and chili powder together for 5 minutes. Add in oregano, tomatoes, salt, and stock, simmer on low for at least 5 more minutes (though the longer it simmers the better it is).
In cast iron skillet, layer tortillas and sauce. Top with cheese and place in the oven for 5 minutes, or until cheese is melted. Now would be a good time to cook optional eggs, chorizo, slice avocado, and chop cilantro.
Once tortillas are cooked and cheese is melted, remove and top with onion, cilantro, pickled jalapenos, avocado, and optional chorizo/eggs.