We don’t normally eat potato dishes like potatoes au gratin. But our friend recently gave us a Cooking Light magazine with some interesting recipes we thought we’d try. This two-potato gratin uses sweet potatoes for an extra bump of richness, and the fat levels are low enough to not send you into a food coma after eating a side of this dish.
Preheat the oven to 350.
Prepare the Potatoes Peel 2 medium baking potatoes and slice into 1/4-inch thick rounds. Do the same for 2 medium sweet potatoes. Put the potatoes in a large stockpot, cover with no-salt-added chicken stock and bring to a boil. Cook for 4 minutes, remove from the heat, and remove the potatoes using a slotted spoon. Reserve the cooking liquid.
Arrange the potato slices in a single layer on a cookie sheet and set aside. Reserve 1 cup of the cooking liquid. Discard the rest.
Make the White Sauce Heat a medium saucepan over medium heat and add 2 tsp canola oil to the pan. Sprinkle 3 T flour over the oil. Cook 1 minute, stirring constantly with a whisk. Add 2 crushed garlic cloves and cook another 2 minutes, stirring all the while. Combine 1 1/2 cups 2% milk and 1 cup cooking liquid, then gradually pour the mixture into the flour mixture, stirring constantly with the whisk.
Add 2 thyme sprigs and bring the mixture to a boil. Cook for 4 minutes until slightly thick, stirring constantly. Remove from the heat and pull out any solids with a slotted spoon. Stir in 1/2 tsp salt, pepper and 3/4 cup shredded gruyere cheese.
Do the Layers Pour 1/2 cup of sauce in the bottom of a broiler-safe 2-quart ceramic baking dish. Lay down a single flat layer of potato slices over the sauce. Pour a little more sauce over the layer and then layer in, like shingles, the layers of potato slices. Top with the rest of the white sauce.
Sprinkle evenly with 1/4 tsp salt, 1 T chives and chopped thyme, and top with 1/4 cup grated Parmesan-Reggiano cheese. Bake at 350 for an hour. Remove the gratin from the oven. Preheat the broiler to high and broil 3 minutes or until browned. Sprinkle with a few more chopped chives and serve.