Trim potatoes into squared sides. Proceed to slice them into evenly sized fries.
Make sure the fries are dry. In a large bowl, mix them with oil, salt, & pepper.
Place in a single layer on a parchment-lined baking dish and bake at 450° for 45 minutes.
While they bake, prepare the gravy by melting the butter in a saucepan over medium heat then adding the flour. Whisk until smooth, making a roux.
Pour in stock and whisk until it comes to a boil then simmer.
Season with salt & pepper and simmer until it reaches your desired thickness.
When the fries are done, place on a foil-lined pan and layer the cheese over them. Broil for 1-2 minutes.
Serve the fries with the gravy poured on or on the side for dipping.