Preheat the oven to 200°C. Line an oven tray with baking paper. Trim the cauliflower and cut into small florets. Spread florets and chickpeas over the baking tray.
Mix together the Marmite with the sesame seeds, ground cumin, honey and olive oil. Stir well. Season to taste with freshly ground black pepper. Mix in 2 tbs boiling water to help dissolve the mix. Pour mixture over the cauliflower and chickpeas and toss to evenly coat.
Place tray in oven and cook for 20 minutes until cauliflower is tender and fragrant. Allow to cool slightly.
Make the dressing by mixing together the yoghurt, hummus, cucumber, mint, lemon and mustard together in a small bowl. Season to taste.
Assemble the salad, toss together the roasted cauliflower and chickpeas with the spring onions and baby spinach or kale leaves. Serve with dressing on the side.