Preheat your oven to 350°F (175°C).
In a large skillet, heat olive oil over medium heat. Add chopped onion and sauté until softened, about 3 minutes.
Add minced garlic and cook for an additional 1 minute until fragrant.
Add ground beef to the skillet, breaking it apart with a spatula. Cook until browned and cooked through, about 5-7 minutes.
Drain any excess grease if necessary, then stir in the taco seasoning and a splash of water. Mix until combined and cook for another 2-3 minutes.
On a baking sheet, spread out the tortilla chips in an even layer. Spoon the seasoned beef mixture evenly over the chips.
Sprinkle shredded cheddar cheese generously over the top.
Bake in the preheated oven for 10 minutes, or until the cheese is bubbly and melted.
Remove from the oven and top with diced tomatoes, jalapeños, and black olives if using.
Serve the nachos hot, with sour cream, salsa, and chopped cilantro on the side for dipping.