Preheat the oven to 200 ̊C/400°F/gas mark 6. Line a large roasting pan with baking paper.
Toss the sweet potato and red onion with 1⁄2 tablespoon of the olive oil and put into the prepared pan. Season with salt and pepper and roast for 20 minutes.
Meanwhile, bring a large saucepan of water to the boil, add the stock (bouillon) cube and stir to dissolve. Add the spelt and reduce to a simmer, then cook for 25–30 minutes until the spelt is tender but still a little chewy.
Add the cavolo nero or kale to the vegetables in the roasting pan and return to the oven to roast for a further 5–7 minutes, or until the greens are starting to crisp up.
Drain the spelt and add it to the roasting pan along with the chilli and roast for a final 5 minutes.
Heat the remaining 1⁄2 tablespoon of olive oil in a large frying pan (skillet) over a medium heat. Add the cheese to the pan and fry for 5 minutes, or until golden and slightly melted.
Mix together the dressing ingredients and season to taste.
Serve the roasted salad while still warm, topped with the cheese slices and with the dressing drizzled over.