1 large sheet of frozen puff pastry, (8 1/2-inch to 14 inches), defrosted

1 large egg, beaten

2 tablespoons freshly grated Parmesan cheese

1. Put the onions in a large mixing bowl. Immerse the carrots and potatoes in a medium pan of boiling water and simmer for about 10 minutes or until tender. Remove, drain and add the vegetables to the onions.

2. In a medium skillet melt 2 tablespoons of butter on medium heat. Add the leeks and saute for about 4 minutes or until nicely softened. Add all the mushrooms and continue to saute for 3 more minutes or until softened. Add the leeks and mushrooms, along with the cooking juices, to the other bowl of vegetables. Add the peas, corn and turkey chunks to the vegetables and reserve.

3. Melt the remaining 6 tablespoons of butter in a large saucepan on medium heat. Sprinkle in the flour and cook, stirring constantly for 3 minutes. Slowly add the stock and half and half, then add salt and pepper and whisk the sauce until it is thickened and smooth, about 3 more minutes. Add salt and pepper to taste. Pour the sauce over the turkey and vegetable mixture along with the herbs and mix well. Taste for seasoning.

4. Grease a large, deep casserole (9-by-13 inch) dish with butter. Pour the mixture into the casserole dish.

5. Preheat the oven to 400 F. If necessary, roll out the pastry on a lightly floured surface to a 14-by-10 inch rectangle. Brush the rim of the dish with water. Cover the filling with the pastry, making sure to press it against the dish. Brush the beaten egg over the pastry. Make 3 slashes in the pastry and bake on a baking sheet for 40 to 45 minutes. Sprinkle the Parmesan cheese on the last 15 minutes of baking time to brown the crust. Remove from the oven and let sit for 10 minutes. Serve.

Make Ahead: You can make this a day ahead through Step 4, cover well and refrigerate. It also may be baked completely ahead, refrigerated, covered, brought to room temperature and then gently reheated in a 325 F oven for 20 minutes or until bubbling.

(Diane Rossen Worthington is an authority on new American cooking. She is the author of 18 cookbooks, including "Seriously Simple Parties," and a James Beard Award-winning radio show host. You can contact her at www.seriouslysimple.com.)