1. Preheat oven to 450°F (232°C) and spray a 12-cup bundt pan with cooking spray.
2. In a large skillet over medium-high heat, cook the ground beef, diced onion, salt, and pepper until beef is fully browned and no pink remains, about 6-7 minutes. Drain excess fat.
3. Return skillet to heat, add water and taco seasoning, cook for 2-3 minutes until most liquid evaporates, then remove from heat.
4. Layer the bundt pan starting with half the shredded cheese, followed by half the beef mixture, then one-third of the tortilla chips. Do not pack chips tightly.
5. Repeat layering with remaining cheese, beef, and another one-third of tortilla chips evenly without overfilling.
6. Bake for 10 minutes or until cheese is melted and bubbly.
7. Remove bundt pan from oven, place a heat-proof large plate inverted on top, and carefully flip to invert nachos onto plate. If cheese sticks, gently place it back on top.
8. Serve immediately with optional toppings like sour cream, diced tomatoes, cilantro, guacamole, or salsa.