Preheat oven to 350 degrees. In a skillet, heat 2 T olive oil over medium heat. Add 2 leeks sliced thinly and add 2 T water. Season with salt and pepper. Cook until leeks are browned - about 10 minutes. Stir often. Add 1/2 c. sherry and 1 T chopped sage leaves. Cook until the liquid is reduced to a glaze (3 min.)
Butter a shallow baking dish and arrange thin slices of butternut squash (1 pound). Season with salt and pepper. Cover with leek mixture.
Slice and peel about 3 large apples (1/8 inch slices). Arrange sliced apples such as Gala, Macoun, Cortland over the leeks. Brush apples with 1 T. olive oil. Cover tightly with parchment and foil. Bake 45 minutes.
Uncover, sprinkle with finely grated Parmigiano-Reggiano cheese. Raise oven temp to 450 degrees and back until cheese is melted (10 minutes.)
Garnish with sage leaves.
