Preheat oven to 350°F. Spray a 2-quart baking dish with nonstick spray.
Spread ¼ cup of enchilada sauce in a thin layer in the bottom of the prepared dish. Set aside.
In a large skillet, cook the ground beef over medium-high heat until no longer pink. Drain off the excess fat. Return the beef to the skillet and stir in ¾ cup of enchilada sauce and ½ cup of the cheese.
Arrange 4 of the tortillas in the bottom of the dish, tearing or overlapping them as needed to cover the base.
Spread half of the beef mixture over the tortillas, then drizzle with ¼ cup of enchilada sauce. Repeat with a second layer of 4 tortillas, the remaining beef mixture, and another drizzle of sauce.
Cover with foil and bake for 30 minutes.
Remove the foil, sprinkle with the remaining ½ cup of cheese, and bake uncovered for an additional 5 to 10 minutes, until the cheese is melted and the casserole is hot and bubbly.
Garnish with optional toppings and serve.