Heat a few tablespoons of oil in a large skillet over medium-high heat. Fry the tortillas, one at a time, until crisped and browned on both sides. Drain on paper towels and set aside to cool.

Drain all but about 1 teaspoon of oil from the pan, then add the beef. Break it up with a wooden spoon and cook until browned, about 8 minutes. Transfer to a bowl and set aside.

Heat the remaining 1 tablespoon oil in the pan and add the onion, garlic and jalapeño. Cook, stirring, until softened, about 5 minutes. Add the cumin, chili powder, salt and pepper, then cook until fragrant, about 1 minute more. Stir in the tomatoes and tomato paste, then add the beans and reserved ground beef. Simmer for about 5 minutes, or until much of the liquid has evaporated.

Add the corn and spinach, tossing until the spinach wilts and the corn is heated through. Taste and adjust seasoning as needed.

To assemble, place one tortilla in the prepared pan and spread about ⅙ of the filling evenly over the top. Sprinkle with about ⅙ of the cheese, then top with another tortilla. Repeat with the remaining filling, cheese and tortillas, finishing with a layer of filling and cheese on top.

Bake, uncovered, for about 20 minutes, or until lightly browned on top and heated through. Let rest for at least 5 minutes before removing from the pan.

Sprinkle with cilantro, scallions or both if desired. Use a sharp knife to cut into wedges and a spatula or pie server to lift them out. Serve hot with sour cream, salsa or guacamole on the side.