Toss your cubed squash in the tsp of chilli powder and light drizzle of olive oil, place on a baking tray in the centre of the oven and roast for 40 minutes, or until the edges of the squash are starting to crisp.
When the butternut squash has 10-15 minutes remaining, heat a large pan on low heat. Once hot, add the oil, onion and chopped garlic. Sautee for 4-5 minutes, then add the rosemary and cook for a further minute.
Then add the tomato puree and chickpeas, increase the heat slightly to a low medium stir thoroughly so the oil residue and tomato puree mix and everything is evenly coated. Cook for a further 4-5 minutes, then add the seeds. Leave them for roughly one minute before stirring them in, add your cooked butternut squash to the pan, stir thoroughly again.
Finally, add the tamari, stir, leave on the heat for a further 30 seconds to a minute then remove from the heat and serve. Stir in the olives before serving, if using.