Heat your oven to 200°C/Fan 180°C/Gas 6. Halve the squash and scoop out the seeds. Slice the squash into wedges (you don't have to peel them but you can if you prefer to). Pop in a roasting tin.
Tip 6 cardamom pods into a mortar. Lightly crush with the pestle to open the husks. Keep the seeds in the mortar and discard the husks. Add 1 tsp each cumin and fennel seeds, ½ tsp cinnamon and a pinch of chilli flakes (they're spicy, so use as much or as little as you like). Stir together.
Drizzle 1 tbsp oil over the sqaush. Add half the spice mix and some seasoning. Turn the wedges to coat them in the oil and spices. Slide onto the top shelf of your oven. Set the timer for 30 mins.
Drain the chickpeas and add them to the bowl. Peel the onion and slice into wedges. Peel and crush the garlic. Add them to the bowl with the remaining spice mix and ½ tbsp oil. Season and toss together. Spread out on a baking tray. Slide onto a shelf below the squash and roast for 25 mins (see our tip for timings).
Tear the soft kale leaves off the hard cores. Put the leaves in the bowl and swirl them round to pick up any leftover oil and spices. Massage them for 2 mins, then set aside.
While everything roasts, tip the buckwheat into a pan and toast for 5 mins till darkened and nutty smelling. Tip into a bowl and set aside.
After the chickpeas have roasted for 25 mins, add the kale and pumpkin seeds and roast for a further 5 mins till a little browned.
Grate or pare the zest off the lemon and set aside. Juice the lemon. Mix the juice with the tahini, ½ tbsp oil and 2 tbsp water. Stone the dates and roughly chop them.
The squash should be tender and a little charred, and the kale and chickpeas browned. Arrange the squash, kale, chickpeas and onion on warm plates. Drizzle over the tahini sauce. Scatter over the dates, toasted buckwheat and lemon zest to serve.