To make the chicken mousseline, first put the chicken in the freezer for 30 minutes to ensure it is cold enough to work with. Then, remove the skin and set aside for later. Dice the chicken breast into small chunks and blend in a food processor until completely smooth.
Whilst the food processor is still blending, add the egg to the chicken and continue blending until the egg is fully incorporated. Next, pass the blended chicken mixture through a very fine sieve.
Place the bowl with the chicken over a bowl full of ice, and gradually mix in the double cream. Season with salt and pepper. Once done, place the chicken mixture in the fridge to cool down ready for shaping.
In the meantime make the duxelle by blending the mushrooms in the food processor until they are finely chopped and put into a dry sauce pan over a medium heat to remove any excess moisture. Season with salt and pepper.
Finely chop some tarragon and add it to the duxelle and cook for another 2 minutes. Once cooked, set aside to cool.
To assemble the chicken and mushroom Ballantine, spread the chicken mousse onto a piece of cling film in the shape of a rectangle, and lay some of the duxelle mixture horizontally along the middle. Carefully lift the cling film from the bottom and fold the chicken mousse into a sausage shape, then roll the cling film up tightly. Set aside in the fridge until ready to cook.
Peel and chop the potatoes and bring them to the boil in a pan of salted water. Once cooked, drain and leave to steam for a couple of minutes. Mash the potatoes until smooth adding a knob of butter and a splash of milk. Set aside until later.
Slice the carrots length ways (skin on) and place cut side down onto an oiled baking tray and season with salt and pepper. Scatter the garlic cloves into the same baking tray and then roast at 180°C for 40 minutes or until the carrots are soft. Once cooked, transfer the roasted carrots to the food processor and blend until very smooth. Pass the carrot puree through a fine sieve and put into a squeezy bottle.
Remove the roasted garlic cloves from their skins and mash with a fork. Add the mashed garlic to the mashed potato and mix thoroughly.
Put the chicken skin on a baking tray lined with parchment and season with salt and pepper, place another sheet of parchment and another tray on top of the skin to weigh it down and place in the oven for 30 minutes or until the skin is completely crispy. Once cooked, pat the skin dry with kitchen roll, and blend in the processor into a fine powder. Pour the chicken powder evenly onto a plate and set aside for later.
For the pea purée, simply steam the frozen peas for 2 minutes, then blend with a hand blender and pass through a fine sieve. Season with salt and pepper and put into a squeezy bottle ready for later.
For the sauce, add the wine to a sauce pan and reduce by half. Then add the Oxo chicken stock and the cream and reduce again by half. Once reduced, add the tarragon and remove from the heat. Leave to infuse for a few minutes then strain the sauce through a sieve. To thicken the sauce, add Thick and Easy and stir until the desired consistency is reached.
Remove the chicken mousse from the fridge and steam gently for approximately 30 minutes at 80°C. Meanwhile, warm up the rest of the dish components ready to serve. Once the mousse is cooked, remove from the steamer and leave to rest for a couple of minutes. Remove the cling film from the mousse and roll it in the chicken skin powder.
Pipe the garlic mash onto the plate, then slice the chicken mousse into three pieces. Place the mousse on top of the mash and add the purées to the plate. Finally, spoon over some of the tarragon sauce and serve.