Preheat your oven to 200 °C. Pop the chicken thighs on a lined baking tray and drizzle on a splash of oil. Season with salt, pepper and half the dried thyme. Use your hands to rub the flavours all over the meat. Roast the chicken thighs on the top shelf of your oven until golden and cooked through, 30-35 mins.
Chop the new potatoes into 2cm chunks. Remove the ends from the carrot, quarter lengthways then chop into 3cm long batons. Halve, peel and chop the onion into six even wedges. Put all the veggies on another lined baking tray in a single layer and drizzle over a splash of oil. Season with salt and pepper and sprinkle over the remaining dried thyme.
Toss to coat in the seasonings, then roast on the middle shelf of your oven until the veggies are golden and soft enough to eat, 20-25 mins. Turn halfway through cooking
While your chicken and potatoes are cooking. Peel and grate the garlic (or use a garlic press) then heat a frying pan on medium heat and add the butter. Once the butter has melted, add the cavolo nero, stir, add a splash of water, and the garlic and pop on a lid. Cook until the leaves are tender, 4-5 mins, stir every now and then. When ready, season with salt and pepper and keep to one side
When the chicken is ready, remove from the oven and leave to rest for a few mins before serving.
Reheat the cavolo nero if necessary then share between your plates. Leave any excess water behind. Top with the chicken thighs. Serve the roasted veggies alongside and finish with a dollop of mayo. Enjoy!