Preheat oven to 425 F (218 C) and line a baking sheet with parchment paper. Slice your squash in half lengthwise and remove the seeds, but leave the skin on. Rub squash flesh with a bit of oil. Place garlic cloves on the prepared baking sheet and top with squash cut side down (the scooped-out squash should cover the garlic so it doesn’t burn). Bake for 30-40 minutes, or until the skin is blistered and golden brown and a knife inserted into the squash comes out very easily.
While the squash is cooking, bring a large pot of salted water to a boil. Cook the lasagna noodles in the salted water according to package instructions or until al dente. Then drain, set aside, and gently toss with a little olive oil to prevent the noodles from sticking together.
Heat a large rimmed skillet over medium heat. Once hot, add the olive oil and onion and sauté for 3-4 minutes or until softened, then add the mushrooms and sauté another 5-7 minutes or until lightly browned. Then add kale, salt, pepper, and thyme (optional) and sauté for another 5-7 minutes or until tender.
Once the squash is tender and cool enough to handle, scoop 2 cups (~480 g) roasted squash (adjust amount if altering number of servings) into a high-speed blender. Add roasted garlic cloves, cashews, lemon juice, salt, nutritional yeast (optional), and water and blend until smooth, adding more water and scraping down the sides of the blender as needed. It should be thick, creamy, and scoopable. Taste and adjust as needed, adding more salt for overall flavor, lemon for brightness, garlic for savory flavor, or nutritional yeast for cheesiness.
Reduce oven temperature to 350 F (177 C).
Assemble the lasagna in a 9 x 13 (or similar size) glass or ceramic baking dish. Add 1/2 cup (120 ml) sauce to the bottom of the pan and spread it evenly. Then add a layer of noodles followed by 1/3 of the filling. Repeat with two more layers of sauce, noodles, and filling. Then finish with a layer of noodles and the remaining sauce as the top layer (it should be a thicker layer fully coating the noodles).
Bake lasagna at 350 F (177 C) for 30 minutes or until the top layer is slightly dry and a little darker in color.
Carefully remove from the oven and let cool 5-10 minutes before serving. Then slice, serve, and enjoy. We recommend garnishing with freshly chopped basil and vegan parmesan cheese. See notes below for freezing instructions.
*To make this recipe freezer friendly, prepare as instructed. Once assembled, cover well and freeze up to 1 month. To bake, preheat oven to 350 degrees F (176 C), cover with foil, and bake for 25 minutes (if thawed) or up to 45 minutes – 1 hour (if frozen). Then remove foil and bake for another 5-10 minutes or until sauce is bubbly and hot. *Nutrition information is a rough estimate calculated with 1/4 tsp of the salt in the pasta water (since the full tablespoon isn’t absorbed into the pasta) and without optional ingredients.