01 -
Cook frozen fries according to the package in an uncrowded layer, or cut fresh russets into even quarter-inch sticks. For fresh fries, heat the oven to 450°F, dry the sticks and toss with the two tablespoons of oil.
02 -
Roast across enough trays to avoid crowding, turn partway through and check from twenty minutes until tender and browned. While the fries finish, melt butter in a saucepan over medium heat. Stir in flour and cook for one to two minutes without letting it darken.
03 -
Whisk in the measured milk gradually until smooth and lightly thickened. Remove from heat and stir in cheddar in handfuls until melted; loosen with a little extra milk only if needed.
04 -
Season the hot fries with Cajun seasoning, starting with one tablespoon. Spoon the thick cheese sauce over individual servings and drizzle with ranch. Serve at once with extra dressing alongside.