Preheat oven to 375 degrees. Coat an 8 x 8-inch baking dish with nonstick spray.
Heat oil in a large frying pan over medium heat. When hot, add onion. Season with salt, then cook until translucent and tender (about 5 minutes).
Stir garlic, cumin, chili powder, oregano, smoked paprika, and red pepper flakes into pan. Cook, stirring constantly, until fragrant (about 30 seconds).
Add black beans, pinto beans, tomatoes, corn, and olives to pan, plus ¼ cup water. Bring to a simmer, then cook until hot (about 5 minutes).
Remove from heat, then season to taste with salt.
Add half of the tortilla chips to the baking pan. Top with half of the bean mixture. Sprinkle with half of the cheese. Repeat these layers (chips, filling, cheese) one more time.
Bake casserole until hot (about 20 to 25 minutes).
Serve hot. Enjoy!
Notes
Serving a crowd? Double the recipe and bake it in a 9 x 13-inch pan instead.Make sure to read all the info before this recipe card for more tips, variations, and related recipes!