To prepare the butternut squash: Preheat the oven to 425. Slice the butternut squash in half, lengthwise. Drizzle with 1 tablespoon of olive oil, sprinkle with garlic, sage, allspice, and salt. Flip the squash over so that the inside is face-down on the baking sheet and bake for 40 minutes, until very tender.
To make the bechamel sauce, heat vegan butter in a medium saucepan over medium-high heat. Once butter is melted, add flour and stir over heat for 3-4 minutes, until the mixture is smooth and golden-brown. In another pot, bring milk, minced garlic, nutmeg, and salt to a boil. Add hot milk to butter/flour mixture in 3 batches. Bring to a boil, whisking often, then reduce heat to a simmer. Cook for 10 minutes, whisking constantly. Once thick and creamy, remove from heat and set aside. The sauce will continue to thicken as it cools. In a skillet, heat the additional 1 tablespoon of olive oil over medium-low heat. Add sliced onions and sauté slowly, stirring occasionally, for about 15 minutes. Once onions are soft and lightly browned, stir in chopped kale. Sauté for another 5 minutes until kale is cooked.
When the butternut squash is done, remove from heat and reduce oven to 375 degrees. With a spoon scoop out squash from the skin and place in a large bow. Mash it the back of a wooden spoon or potato masher until it's smooth and creamy. A few lumps are okay.
Once everything is ready, it's time to assemble. In a 9x13 baking dish, pour a small amount of Bechamel Sauce on the bottom and spread evenly. Lay down a layer of noodles followed by Bechamel Sauce, mashed butternut squash, and then sautéd kale. Top this with more Bechamel Sauce and repeat the process. Top with the 3rd layer of noodles and the final layer of Bechamel. Cover in foil and bake for 40 minutes. Remove from heat and let cool 15 minutes before slicing. Top with vegan parmesan cheese and/or parsley and serve.