Preheat oven to 400F. Cut kabocha squash in half and scoop out seeds using a spoon. Slice into 1-in wedges.
In a small bowl, whisk together the walnut oil, cinnamon, nutmeg, and ginger. Toss wedges with oil and spice mix and arrange on a baking sheet. Roast for 25-30 minutes until the squash begins to brown on the edges and becomes soft. While squash is cooking, whisk together the miso, maple syrup, and rice wine vinegar. Take out the pan during the last 5 minutes of cooking and brush the miso sauce on top of each slice. Place pan back into oven to finish cooking. Serve with fried sage, walnuts, and pomegranate seeds.