Heat your oven to 200°C/Fan 180°C/Gas 6. Peel the celeriac. Chop into small 1 cm chunks. Place in a roasting dish. Season. Toss with ½ tbsp oil. Slide into the oven and roast for 10 mins.
Peel the ginger and turmeric with the side of a teaspoon. Peel the garlic. Finely grate all three. Halve the chilli and flick out most of the seeds. Finely chop it. Pop into a bowl and mix with 2 tsp garam masala to form a paste.
Crumble the stock cube into a heatproof jug. Pour over 400ml boiling water. Stir to dissolve the stock
cube. Swirl in the paste.
Peel and core the apple. Coarsley grate it. Finely chop the coriander leaves and stalks. Keep them separate.
After the celeriac has roasted for 10 mins, remove it from the oven. Fold through the grated apple. Sit the chicken breasts on top. Pour over the fragrant stock. Drizzle the chicken with ½ tbsp oil. Season. Slide into the oven and roast for 25 mins.
While the chicken is cooking, tip the rice into a bowl. Cover with cold water. Whisk the rice for 1-2 mins till the water turns cloudy. Drain the rice. Rinse under cold water.
Tip the rice into a small pan. Pour in 300ml boiling water. Add a pinch of salt. Cover. Bring to the boil.
Turn the heat right down. Gently simmer for 8 mins till the water is absorbed and the rice is tender. Take off the heat. Set aside, lid on, for 5 mins to finish cooking the rice.
Remove the chicken from the oven and lift onto a plate. Cover with foil. Tip the celeriac and apple into a food processor with any remaining stock. Blitz to a smooth purée with the coriander stalks. Alternatively, mash with a masher for a chunkier, but just as delicious, sauce. Serve with the rice and chicken. Scatter over the coriander leaves.