Peel the butternut squash and remove and discard the seeds. Chop the flesh into smallish chunks - you want them small so they don't take long to cook through
Thinly slice the leek (give a rinse in cold water) and peel and finely chop the garlic
Heat the oil and butter together in a large saute pan and add the chopped squash. Cook, stirring from time to time, for around 10 minutes over a medium/high heat until the squash starts to caramelise
Add the leek and garlic and cook, stirring, for a couple more minutes
Add the tomatoes, balsamic vinegar, rosemary, stock cube, miso paste and 1/2 cup (125ml) water. Bring the boil then simmer for 10 minutes or until the squash is soft and cooked
Transfer the sauce to a food processor or blender and blitz until smooth
Season to taste then stir the sauce through cooked pasta
Cool any extra sauce and store in the fridge or freezer
Recipe by The Cook & Him at https://thecookandhim.com/recipes/butternut-squash-pasta-sauce/