Preheat the oven 400 degrees F. In a sauce pan, over medium heat, combine the vegetable oil and flour together. Cook the roux, stirring constantly, for 4 to 6 minutes for a blond roux. Whisk in the milk and bring the liquid up to a boil. Season with nutmeg, salt and pepper. Reduce to a simmer and cook for 6 to 8 minutes or until the sauce coats the back of a spoon. Fold in the cheese. Layer the potatoes in a gratin dish. Pour the cheese sauce over the potatoes. Sprinkle the top with bread crumbs. Place the dish in the oven and bake for 15 minutes or until the potatoes are tender and the top is golden brown. Remove from the oven and let rest for 5 minutes before serving. Garnish the potatoes with chives and serve.