Turn the oven on at 180 degrees Celsius. Add the butternut squash cubes and shallots to a roasting tray together together with the rosemary. Drizzle with the olive oil, salt and pepper. Give the tray a good shake so everything is coated. Roast in the oven for 25 minutes until the butternut squash is soft.
In the meantime add the remaning oil to frying pan together with the crushed garlic. Sautee for few minutes then add the chopped kale. Cook for another 3-4 minuets until the kale is wilted. Make sure to keep stirring to prevent the garlic from burning.
Cook the pasta according to the packet’s instructions.
Transfer half of the butternut squash cubes (not the shallots) into a bowl and add in the mustard, nutritional yeast and 4 tablespoons of the pasta cooking water. Mash everything up with a fork until you have some kind of puree.
Drain the pasta and tip it into the frying pan with the kale. Add in the butternut squash puree, roasted butternut squash cubes and shallots and mix everything well. Serve with the crushed walnuts, some black pepper and some chilli flakes (if using).