Peel, then top and tail the squash. Scoop the seeds out with a spoon and discard. Trim the leek. Strip the silks from the corn and carefully slice the kernels away from the cob. Put all of the veg trimmings into a pan and cover with 1.25 ltr water. Bring to a simmer.
Halve the leek lengthways and slice thinly. Pour 1 tbsp oil into a large pan and bring to a medium heat. Add the leek and soften for about 5 mins.
Chop half the sage and finely chop the garlic. Stir into the leeks along with the 1 tsp cinnamon, 1 tsp smoked paprika and a generous sprinkle of seasoning.
Cut the squash into 1cm-sized cubes. Tip into the leek pan and stir well to coat with the spices. Fry for a further 1 min, then add the pearl barley.
Use a sieve to strain the stock into the veg, adding a splash of water if needed to cover. Bring to the boil and pop the lid on at an angle (leaving a little gap). Simmer for 20 mins.
Strip the kale leaves, discarding the thick stalks, and roughly shred. Stir into the soup along with the sweetcorn kernels. Cook for 4-5 mins.
To thicken the soup, use a stick blender to blitz till it's as smooth as you like. Or leave it as a chunky broth. Set a frying pan over a high heat with a gloss of oil. Pluck the remaining sage leaves from their stalks. Fry the sage leaves with a pinch of salt till crisp.
Taste and adjust the seasoning if needed, then spoon into deep bowls. Finish with the crispy sage leaves.