Preheat your oven to 400°F and line a large baking sheet with foil for easy cleanup. Spread about half your tortilla chips across the sheet in a single layer, creating your foundation.
Brown the ground beef in a skillet over medium-high heat, breaking it apart as it cooks. Once no pink remains (3-4 minutes), add the diced onion, cumin, and chili powder, stirring constantly for another minute until fragrant.
Drain excess fat from the beef mixture, then stir in the black beans and corn. Let it warm through (1-2 minutes), then remove from heat and set aside.
Sprinkle the cheddar cheese evenly over your chip layer, then add the beef mixture on top. Scatter mozzarella cheese over the beef, ensuring gooey loaded game day nachos recipe components are distributed evenly for consistent melting.
Bake for 5 minutes until cheese is completely melted and bubbly at the edges. Watch carefully so chips don't burn—your oven may vary, so start checking at 4 minutes.
Remove from oven and immediately top with fresh jalapeños, cilantro, green onions, and remaining tortilla chips. Drizzle with salsa and dollops of sour cream for serving.