01 -
Set oven or air fryer to 400°F (204°C) to preheat.
02 -
Arrange frozen French fries in a single layer on a baking sheet or air fryer basket. Bake according to package instructions until golden and crisp.
03 -
Melt butter in a medium saucepan over medium heat. Whisk in all-purpose flour and cook for 2 minutes, stirring constantly.
04 -
Gradually whisk whole milk into the roux. Add salt, ground white pepper, ranch seasoning powder, and half of the cayenne powder. Reduce heat to medium-low and cook, whisking, until sauce thickens, about 5 minutes.
05 -
Stir shredded white cheddar cheese into the sauce. Continue stirring until cheese is fully melted and sauce is smooth.
06 -
Pour hot cheese sauce evenly over crispy baked fries. Sprinkle remaining cayenne powder on top and serve immediately while warm.