For the Enchilada sauce

Heat the canola oil in a large saucepan over medium heat and whisk in the flour. Cook, whisking constantly, for one minute, then whisk in the chili powder, chipotle powder, and cumin. Add the stock, bring to a boil, lower the heat, and simmer for a few minutes until slightly thickened. Stir in the fire-roasted tomatoes, crushed tomatoes, oregano, and 1 tablespoon salt, bring to a boil, then lower the heat and simmer for 20 minutes, stirring occasionally.

For the Chilaquiles

Preheat oven to 400 degrees F. Lightly coat a 9-by-13-inch baking pan with cooking spray.

Heat oil in a large nonstick skillet over medium-high heat. Add onion and cook, stirring often, until starting to brown, about 5 minutes. Stir in zucchini, beans, tomatoes, corn, cumin and salt and cook, stirring occasionally, until the vegetables are heated through, about 3-5 minutes. Add protein.

Scatter half the tortilla pieces in the pan. Top with half the vegetable mixture, half the enchilada sauce and half the cheese. Repeat with one more layer of tortillas, vegetables, sauce and cheese. Cover with foil.

Bake the casserole for 15 minutes. Remove the foil and continue baking until the casserole is bubbling around the edges and the cheese is melted, about 10 minutes more.