Preheat the oven to 425 degrees Fahrenheit. Line a large rimmed baking sheet with parchment paper then add the French fries in an even layer. Bake for 15 to 20 minutes, stirring halfway through to ensure even baking.
In the meantime, add the ground beef and onion to a large skillet over medium heat. Crumble the beef and cook until browned, about 10 minutes. Add the garlic, chili powder, cumin, and salt to the pan and cook for about 2 minutes or until the garlic becomes fragrant.
Stir in the tomato paste, Rotel, and kidney beans and reduce the heat to medium-low. Let it simmer for 15 minutes or until it has thickened.
While the chili is simmering, prepare the cheese sauce by melting the butter in a medium saucepan over medium heat. Whisk in the flour until it starts to turn a light brown color. Stir in the onion powder, garlic powder, chili powder, cumin, pepper, and salt.
Gradually pour in the heavy cream, whisking constantly. Continue to whisk until the sauce starts to thicken. Add cheese to the pan one cup at a time. Allow it to fully melt before adding another cup. Once all the cheese has been added to the pan, continue to whisk until fully melted then remove the pan from the heat.
Add 4-5 large scoops of the chili to the fries then pour the cheese sauce over the top. Serve with freshly chopped parsley or green onions for garnish if desired.