Preheat oven to 425F. Spray an 8x8 casserole or baking dish with coconut oil spray, set aside. Line a sheet pan with parchment paper or silpat. Set aside.
Split and deseed the butternut squash. Drizzle 1 Tbs coconut oil on the flesh and spread it around on the surface. Sprinkle flesh with 1/2 tsp sea salt and all the sage. Turn the flesh face down to roast. Wrap the peeled garlic sprinkled with 2 tsp coconut oil in foil and place on the same pan as the butternut squash. Roast garlic for 30 minutes and butternut squash for 40 minutes. Remove from oven and cool until both can be safely handled. Scrape flesh of butternut squash from the skin and discard skin. Using a potato masher, mash the garlic and butternut squash together (I do this right on the roasting pan). A few chunks are ok. Set aside.
While the squash is roasting, slice the onions. Add 1 tsp of coconut oil to a dutch oven, heat until oil shimmers then add the onions with 1/4 tsp salt. Caramelize the onions for about 25-30 minutes, stirring occasionally, on low heat. The onions should be browned and soft. Spoon into a large mixing bowl.
In the same dutch oven, add the chopped kale with 2 Tbs water on medium heat. Cover and steam for 3 minutes, opening at 2 minutes, stirring, and recovering. The kale should be slightly wilted. Drain any excess water and add to bowl with caramelized onions and stir to incorporate the ingredients.
In a large stock pot bring water to a boil to prepare lasagna pasta. Cook according to package directions. Drain and lay noodles flat and separated onto a dry work surface. It's ok if they cool.
Wipe out the dutch oven and add 3 1/2 C of milk, bay leaf, and thyme. Bring to a boil and remove from heat. Let the herbs steep in the milk for 10 minutes. Remove the herbs and discard. To the reserved 1/2 C of milk, whisk in the all purpose flour. Add the milk/flour mixture into the steeped milk and whisk over medium high heat, whisking until blended. Bring the mixture to a boil. Reduce the heat to medium-low and simmer for about 5 minutes, until thickened, stirring constantly. Remove from heat and stir in the remaining 1/4 tsp of salt, pepper, nutmeg and red pepper flakes. Stir in 3/4 C of the grated fontina. Set aside.
In the prepared 8x8 baking dish spread a scant 1 C milk/cheese mixture in the bottom. Layer in two lasagna noodles. On top of the noodles, spread 1/2 the butternut squash mixture, then 1/2 the kale/onion mixture. Spread a scant 1 C of milk/cheese mixture on top of the kale, then add two more lasagna noodles. Spread the remaining squash on the noodles, then top with the remaining kale and a scant 1 C of the milk mixture. Finish the lasagna off with the last two lasagna noodles and the remaining milk/cheese mixture.
Cover with foil taking care not to touch the surface of the lasagna with the foil. Bake at 425F, covered, for 30 minutes. Remove the foil and add the remaining fontina. Broil for 2-3 minutes or until cheese on top is lightly browned and bubbly. Let stand for 15 minutes before serving. Serve with parmesan and parsley. Let stand for 15 minutes before serving.
Store in a covered container in the refrigerator for up to three days, or freeze for up to two weeks.