Preheat the oven to 375 degrees F. In a large bowl combine all the ingredients, tossing to coat. Season with salt and pepper. Put the potato mixture into a casserole dish, flatten it out with a spatula, and bake for 40 minutes, until the potatoes are tender and the gratin is bubbly. Let stand for 10 minutes before serving. Garnish with fresh chives.
Recipe courtesy of Tyler Florence