Preheat oven to 200c, 400f (gas mark 4)
Brush the half a butternut squash flesh side with 1 tablespoon of ghee or butter place on a baking tray lined with parchment paper, flesh side down.
Place in the oven and bake for approx 45, till softened and slightly caramelized.
In the meantime, place a deep saucepan over a medium heat and add the other tablespoon of ghee, add the onion and fry for about 8-10 mins until softened. Add the garlic and fry for another couple of mins.
Once butternut squash is done, scoop out of skin and add to the saucepan, along with a pinch of cayenne and break up with the back of a wooden spoon.
Add in the stock and bring to a boil.
Add this to a blender and blend till smooth.
Add the blended squash mixture back to the saucepan over a medium heat and stir in the cheese, once melted, reduce heat to low.
Bring a large saucepan of water (seasoned with salt) to a boil, add in the pasta and cook till al dente. Spoon a couple of spoonfuls of the pasta water into the cheesy squash mixture.
Drain the pasta and stir this into the sauce.
Serve immediately and enjoy!!