Fry the potatoes: Heat vegetable oil to 350°F (175°C). Fry the potatoes in batches for about 4-5 minutes until soft but not browned. Remove and let drain. Increase oil heat to 375°F (190°C) and fry again until golden brown and crispy. (Alternatively, air fry or bake frozen fries according to package directions).

Make the cheese sauce: While fries are cooking, melt butter in a saucepan over medium heat. Whisk in the flour and cook for 1 minute to make a roux.

Thicken the sauce: Gradually whisk in the milk to ensure no lumps form. Simmer until the mixture thickens slightly.

Finish the cheese sauce: Remove the pan from heat and stir in the shredded cheddar cheese until completely melted and smooth.

Prepare the Voodoo seasoning blend: In a small bowl, mix the Cajun seasoning, extra cayenne pepper, garlic powder, and paprika.

Season the fries: Place the hot, cooked fries in a large bowl and toss immediately with half of the seasoning blend.

Assemble: Transfer the seasoned fries to a serving platter. Drizzle generously with the warm cheese sauce and the ranch dressing.

Serve: Sprinkle the remaining seasoning blend over the sauces and serve immediately.