Preheat oven to 400F.
Cut squash in half lengthwise and scoop out the seeds. Cut a criss-cross pattern on the squash (you only need 1/2 a squash) and brush with 1 tbsp olive oil. Season with 1 tsp salt.
Once the oven is heated, cook squash on a baking sheet for about 45 minutes.
Next, finely slice your mushrooms.
Heat 2 tbsp of butter in a large pot on medium-low heat.
Cook mushrooms slowly until they become brown and crispy. Try not to move them too much. Once they're done, they will probably only measure about 1/4 cup. Set these aside.
Add 1 tbsp of olive oil to pan.
Next, take casings off the sausages and add to pan. Mash with a fork or the back of a middle spoon and cook until they are no longer pink (probably 3-5 minutes). They will continue to cook in the sauce, so don't overcook here! Set aside.
Finely chop onions, garlic and carrots.
There should be some remaining oil in the pan. Again on medium-low heat, cook onions, garlic and carrots.
As veggies soften, add 1/2 tsp salt, 1 tsp dried thyme, 2 tsp dried rosemary, 1 tsp red chili flakes, parmesan rind and 2 bay leaves.
Add sausage and mushrooms back in and mix to combine.
Add 4 cups of vegetable or chicken stock and bring to a slow simmer.
Once squash is finished and soft, scoop it out in small pieces and add it to the sauce.
Cook uncovered for 2-2.5 hours, until most of the stock has evaporated. Remove parmesan rind and bay leaves. Add kale and salt to taste.
Once done, cook pasta according to al dente pasta instructions. Keep 1 cup of starchy pasta water.
Once pasta is done, add to sauce. Add 1/2 cup of pasta water and mix. If sauce isn't sticking to pasta well, add remaining 1/2 cup. Finish with 1/2 cup of parmesan cheese.