1. Preheat oven to 425 degrees F. Lightly grease a 15x10x1-inch baking pan. Place squash in the prepared baking pan. Add oil and 1/2 teaspoon salt; toss gently to coat. Spread in an even layer. Roast, uncovered, for 25 to 30 minutes or until squash is tender, stirring once. Reduce oven temperature to 375 degrees F.
2. Meanwhile, for sauce: In a large saucepan, heat butter over medium heat. Add garlic; cook and stir for 1 minute. Stir in flour and 1/2 teaspoon salt. Gradually stir in milk. Cook and stir until thickened and bubbly. Stir in squash and rosemary.
3. Lightly grease a 13x9x2-inch baking dish or 3-quart rectangular casserole. To assemble, spread about 1 cup of the sauce in the the prepared baking dish. Layer three of the noodles in dish. Spread with one-third of the remaining sauce. Sprinkle with 1/3 cup of the Pamesan cheese. Repeat layering noodles, sauce, and Parmesan cheese two more times. Pour whipping cream evenly over layers in dish. Sprinkle with the remaining 1/3 cup Parmesan cheese.
4. Cover dish with foil. Bake for 40 minutes. Uncover and bake about 10 minutes more or until edges are bubbly and top is lightly browned. Let stand for 10 minutes before serving. Makes 8 to 10 servings.