01 -
Preheat oven or air fryer to 400°F.
02 -
Arrange frozen French fries in a single layer on a baking sheet or air fryer basket. Bake until golden brown according to package directions.
03 -
Melt butter in a medium saucepan over medium heat. Whisk in flour and cook for 2 minutes, stirring constantly.
04 -
Gradually add whole milk to the roux, continuously whisking. Stir in salt, ground white pepper, ranch seasoning powder, and half of the cayenne powder. Reduce heat to medium-low and cook, whisking, until thickened, about 5 minutes.
05 -
Stir in shredded white cheddar cheese and continue mixing until cheese is fully melted and sauce is smooth.
06 -
Pour hot cheese sauce evenly over crisp baked fries. Sprinkle with remaining cayenne powder and serve immediately while warm.