Preheat oven to 325 degrees F (165 degrees C). Spray a 9x13-inch baking dish with cooking spray.
Arrange corn tortilla pieces in the bottom of prepared baking dish.
Heat a large skillet over medium-high heat. Cook and stir beef in the hot skillet until browned and crumbly, 5 to 7 minutes; drain and discard grease. Mix ground beef with salsa and garlic salt in a bowl; spoon mixture over tortillas.
Place onion and corn in a food processor; pulse until onion is coarsely chopped. Add milk, 1/2 cup Cheddar cheese, green chile peppers, pimento peppers, eggs, hot sauce, paprika, and salt; pulse until just mixed. Add corn bread mix and pulse until just blended. Spoon corn bread mixture over beef.
Bake in the preheated oven until casserole is set in the middle, 45 to 50 minutes. Top casserole with remaining 1/2 cup Cheddar cheese, olives, and green onions. Let Cheddar cheese melt slightly before serving, about 5 minutes.