Marsala Potatoes au Gratin

Cut each onion lengthwise, then in half crosswise into 1/8-inch slices. Coat a large saucepan with cooking spray (if not non-stick); add oil and heat. Add onion slices and saute (10 min). Add wine and cook until wine is nearly all absorbed (20 min). Remove from heat and stir in thyme. Boil potato slices until "crisp-tender"; drain. Pour cold water over slices and drain well. Arrange one-third of the potato slices into a 13x9x2-inch baking dish coated with cooking spray [or coating of choice], and spoon half of the onion mixture over potato slices. Add another third of potatoes, rest of onion then last third of potatoes. Place flour and salt in a bowl. Gradually add milk, blending with a wire whisk, until smooth. Pour milk mixture evenly over potatoes; sprinkle with Parmesan cheese. Cover with foil and cut 3 1-inch slits in foil. Bake at 350 degrees for 45 minutes. Uncover and bake an additional 15 minutes. Yield: 7 1-cup servings.