Preheat the oven to 350 degrees F (175 degrees C). Spray a 9x13-inch casserole dish with cooking spray.

Cook and stir ground beef and onion in a skillet until beef is browned and crumbly, 5 to 7 minutes. Drain off grease. Stir 1 cup Cheddar cheese, sour cream, taco seasoning, and pepper into the beef mixture until cheese is melted. Mix in red enchilada sauce, chili powder, and salt.

Warm tortillas in the microwave for about 1 minute. Spoon about 1/4 cup of the beef mixture into the center of each tortilla. Roll tortillas up and place in the casserole dish, seam-side down. Spoon any leftover sauce, black beans, and olives over the tortillas. Sprinkle remaining cheese over the top.

Bake in the preheated oven until cheese is melted and filling is bubbling, about 20 minutes.