Preheat your oven to 400 degrees F. Place the frozen french fries on a baking pan in a single layer. Bake according to package instructions, about 25 minutes.
To make the seasoning, stir together the sugar, brown sugar, garlic powder, onion powder, chili powder, cayenne pepper, paprika, salt, and pepper.
To make the cheese sauce, place butter in a small saucepan over medium heat. Once the butter melts, whisk in the flour and keep whisking for 1-2 minutes.
Slowly pour in the milk a little at a time. Make sure to continue whisking.
Turn the heat to medium-low and continue to whisk until the mixture starts to thicken. This will take around 5 minutes.
Turn the heat off and add in the shredded cheese. Remove the saucepan from the heat and stir the cheese until melted.
When the fries are finished cooking, sprinkle them with the seasoning mix.
Place the fries on a serving tray. Top with the cheese sauce and ranch dressing.