Preheat the oven to 425 degrees Fahrenheit. In a large skillet over medium-high heat, add the ground beef and diced onion. Sauté until the beef is mostly browned and the onion is tender.
1 pound lean ground beef, 1 yellow onion, diced
Stir in the tomatoes and taco seasoning. Simmer the mixture until it thickens slightly, then turn off the heat.
1 10- ounce can diced tomatoes & green chilies, 1 packet taco seasoning
Spread the ground beef mixture into an even layer.
Spread about half of the cheese over the meat mixture. Then, spread the tortilla chips evenly over the meat mixture. (Note: For crispier tortilla chips, do not add them before baking. Instead, layer all of the cheese on top of the beef mixture and sprinkle tortilla chips over each serving after plating.)
8 ounces pepper jack cheese, shredded*, 2-3 cups tortilla chips, Fritos, or Doritos
Finally, add the remaining cheese on top of the tortilla chips.
Bake in the preheated oven for 5-10 minutes, or until the cheese is melted and bubbly.