Preheat the oven to 350°F (175°C) and lightly grease an 8×8-inch baking dish.
In a large skillet or pot over medium heat, cook the ground beef until fully browned, breaking it up as it cooks. Drain off any excess grease.
Stir in the taco seasoning and water. Reduce heat to low and simmer for about 5 minutes, or until most of the liquid has been absorbed and the meat is well coated. Remove from heat.
Spread the chili cheese Fritos in an even layer across the bottom of the prepared baking dish.
Spoon the seasoned ground beef evenly over the chips.
In a small saucepan, combine the cheddar cheese soup and milk. Heat over low heat, stirring frequently, until smooth and warmed through.
Pour the cheese mixture evenly over the beef layer.
Sprinkle the shredded mozzarella cheese over the top.
Bake uncovered for 12–14 minutes, or until the cheese is fully melted and bubbly.
Remove from the oven, scoop into bowls or onto plates, and serve warm.
Enjoy!