Combine the butter and flour in a saucepan over medium heat. Stir to blend. Cook, stirring, constantly, to make a dark brown roux, 12 to 15 minutes. Stir in the stock and season with salt and pepper. Bring the mixture to a boil, and then reduce to medium-low and continue cooking for 15 to 20 minutes. Remove from the heat and keep warm. Bring a pot of salted water to a boil. Add the potatoes and blanch for 4 minutes. Remove, drain and cool completely. Fry the potatoes in hot vegetable oil until golden brown. Remove and drain on paper towels. Season with salt and pepper.
To serve, mound the fries into individual (16-ounce) disposable cups. Spoon the gravy over the fries and sprinkle with the cheese. Serve immediately.
Yield: 4 to 6 servings