1. Preheat oven to 375°.
2. Combine first 6 ingredients in a medium saucepan over medium heat; bring to a boil. Reduce heat, and simmer 10 minutes, stirring frequently. Drain potatoes through a sieve over a bowl; reserve potatoes and liquid.
3. Arrange half of potatoes in an 11 x 7-inch glass or ceramic baking dish coated with cooking spray. Spread Duxelles evenly over potatoes; sprinkle with 1/4 cup cheese. Top with remaining potatoes. Pour the reserved cooking liquid over potatoes; sprinkle with remaining 1/4 cup cheese. Bake at 375° for 50 minutes or until cheese begins to brown. Let stand 5 minutes.