4 heritage carrots, in assorted colours, cut into quarters
2 tbsp caster sugar
For the dressing
3 tbsp olive oil
1 tbsp white wine vinegar
1 tsp Dijon mustard
1 garlic clove, crushed
Preheat the oven to 220C/200C Fan/Gas 7.
Mix the herbs and garlic into the butter. Make an incision into the chicken skin and push the skin up with a spoon, push the butter under the skin, smoothing along as you go.
Scatter the hay over the bottom of a lidded casserole dish and add the rosemary. Put the chicken on top and season with salt and pepper. Put the lid on and roast the chicken for 1½ hours.
Meanwhile, make the fennel and carrots. Heat the oil in a frying pan and add the carrots and fennel. Cook for 5 minutes until they are browned and caramelised. Sprinkle over the sugar and dot with the butter. Transfer to an ovenproof dish and roast in the oven for 20 minutes until soft.
Remove the casserole dish from the oven, leave the lid on and allow to rest for 30 minutes.
Spoon a couple of tablespoons of the cooking juices into a bowl and whisk with the dressing ingredients.
Transfer the chicken to a serving plate, place the carrots and fennel around the chicken, drizzle with the dressing and serve.