3 1/2 pounds butternut squash (2 medium) peeled, seeded, cut into 3/4-1 inch cubes
4 medium leeks, sliced (white & pale green parts only)
2 Tbsp fresh sage, chopped
10 oz goat cheese
1 cups heavy cream
1 cup hazelnuts, toasted, husked, coarsely chopped
Toast hazelnuts in 350° oven until they start to smell toasted -10 minutes or so. When they are cool enough to handle, enclose them in a clean dish towel and rub firmly to remove the husks. Chop roughly and set aside.
Cook wild rice by simmering in a large pot with enough water to cover by 1 inch. Add more water as needed to fully cook rice. It takes a while to cook, 45 minutes or so. When rice is tender, remove from heat and drain any excess water. Set aside.
Heat oven to 400°. Toss butternut squash with olive oil, salt, and pepper. Spread on sheet pan. Roast until tender, stirring occasionally, about 35 minutes.
Melt 3 Tbsp in a skillet over medium-low heat. Add sliced leeks, sage, salt & pepper. Sauté until tender but not browned, about 10 minutes.
Coat 11x7 baking dish with remaining 1 Tbsp butter.
Spread 1/2 of the wild rice over the bottom. Layer 1/2 the leeks next, followed by squash. Crumble 1/2 the cheese over squash. Repeat with rice, leeks, squash, and cheese.
Pour cream evenly over gratin.
Top with chopped toasted hazelnuts.
Bake at 375° until gratin is heated through, about 30 minutes.