Directions:

Fire up your oven to 200 Celsius /180 fan-assisted. Let it get really hot while you prep the supper.
Toss the chickpeas, red onion and banana discs onto your largest roasting tray and coat with the spices and preferred oil. Curry powders can vary wildly, so add a pinch of luminous turmeric powder if you fancy a healthy neon glow. I do.
Roast for 15 minutes, or until the banana looks caramelised and the chickpeas are turning crispy. If your roasting tray is small, everything will sweat and turn soggy instead of caramelising so it might be worth spreading over two small trays.
While the chickpeas are raving in the oven, tear the green parts of the cavolo nero off its tough stalk. Gently rip into bite-sized pieces, and tumble into the hot chickpeas. You might need an extra splash of olive oil if everything looks dry. Return to the oven for 3 minutes.