Preheat oven to 350 °F (175 °C). Lightly grease a 9×13‑inch baking dish or oven‑safe skillet.

Heat a tablespoon of oil in a large skillet over medium‑high heat. Add onion and cook until translucent, about 3–5 minutes, then add ground beef. Cook, breaking up meat, until browned (~5–7 minutes). Do not drain fat—this keeps the mixture juicy

Stir in the taco seasoning and salsa. Reduce heat to medium and simmer, scraping up juices, until most liquid is absorbed (~7 minutes)

Stir in the drained beans and warm through (~2 minutes).

Spread crushed tortilla chips in an even bottom layer of the baking dish. Top with beans layer, then the beef mixture. Sprinkle cheese evenly on top

Bake for 20‑30 minutes, or until cheese is melted and casserole is heated through

Remove from oven and let rest briefly. Top with garnishes like sour cream, diced tomato, lettuce, olives, green onion, or cilantro before serving.