1
In a large bowl, combine the ground beef and the baking soda. Mix with your hands until evenly combined. Let sit on the counter for 20 to 30 minutes.
2
Heat the oil in a large skillet over high heat. Add the beef and cook, stirring frequently and breaking into pieces, until just slightly pink, about 2 minutes. Add the chili powder, cumin, and salt and cook, stirring occasionally, for 4 to 5 minutes more, or until cooked through.
3)To assemble: Preheat oven to 350°F and move the oven rack to the center position. Lightly oil a 9x13-in glass or ceramic baking dish.
4
Line the bottom of the prepared baking dish with a layer of tortillas, overlapping them slightly. Spoon half of the beef (and any juices) over the tortillas. Top with 3/4 cup salsa, 1/3 of the cheese. Repeat with another layer of tortillas, the remaining beef, 3/4 cup salsa, and 1/3 of the cheese.
5
Top with the remaining tortillas. Spread 1 cup over the tortillas and cover completely. (You want to ensure that you have enough to cover the top layer of tortillas, otherwise they won't cook through.)Sprinkle the remaining cheese evenly over top.
6
Bake, uncovered, for 30 to 35 minutes, or until the casserole is heated through and the cheese is completely melted.
Note: For a spicier dish, substitute Chipotle chili powder. It is smoky and hot and makes this dish a little spicy.
MAKE AHEAD: The casserole can be prepared ahead of time, tightly covered with foil, and refrigerated for up to two days or frozen for up to 3 months before baking (if frozen, defrost in the refrigerator before cooking). It can also be fully baked, tightly covered with foil, and refrigerated for up to two days or frozen for up to 3 months. To reheat: defrost if necessary and heat the covered casserole in a 350°F oven for about 30 minutes, or until hot. If you'd rather reheat individual servings, small portions can be zapped in the microwave for 1 to 2 minutes.