Heat the oil in a deep frying pan over a medium heat, and fry the shallot with a pinch of salt for 5 mins until soft. Add the squash, garlic, sage and mace, and fry, stirring continually, for another 6-8 mins until the squash is starting to soften and the garlic is fragrant.
Tip in the spinach and barley with some seasoning and the stock. Bring to a simmer and cook for 4-5 mins until the spinach has wilted. Add a splash more stock or water, if you like. When the ‘risotto’ is thick and creamy, taste to see if it needs a little more mace or nutmeg and seasoning. Stir in most of the parmesan, then top with the remaining parmesan and grind over some black pepper to serve.