Preheat the oven to 425 degrees.
Cut the bulbous bottom off the butternut squash (the seeded part.) Slice the top off to ensure that it’s perfectly flat. Peel the butternut squash entirely. If the butternut squash is longer than 6 inches, slice it into two manageable pieces. Slice halfway through the butternut squash, just to the center (careful not to go further.) Spiralize the squash, using Blade A.
Place a large skillet over medium heat and add in the olive oil. Once oil heats, add in the sage leaves and cook until crispy, careful not to burn. Transfer the sage leaves to a small paper towel lined plate and set aside.
Immediately crumble in the sausage to the skillet and cook until browned, 5-7 minutes. Then, add in the kale, garlic, red pepper flakes, shallots and season with salt and pepper. Cook the mixture for 2-3 minutes or until kale is wilted.
While the sausage is cooking, add the ricotta, parmesan and egg to a bowl. Whisk together and set aside.
Once the sausage is done, gather all of your prepared ingredients. Take out a casserole dish (I use 4.2 quart) and add a layer of the butternut squash to the bottom. Then, add a layer of the kale and sausage mixture. Then, add in a layer of ricotta mixture. Top with a layer of butternut squash. Then, add a layer of the kale and sausage mixture. Then, add in a layer of ricotta mixture. Top with a layer of the butternut squash and then, top with all of the gruyere cheese.
Cover the casserole dish with tinfoil and bake in the oven for 40-45 minutes. After 40 minutes, poke the top layer and if you can easily pierce through the butternut squash, it’s done. If you can’t, bake another 5 minutes.
After the 40 minutes of baking, take the dish out of the oven, remove the tinfoil top and immediately sprinkle with sage topping. Then, let rest for 5 minutes. After resting, carefully cut the lasagna into 6 equal portions.