Preheat the oven to 200C/400F/Gas 6.
For the chicken, place the chicken fillets, olive oil and tarragon into a bowl and mix together. Season with salt and freshly ground black pepper.
Heat a griddle pan over a high heat, until smoking, then grill the chicken for three minutes on each side.
Add the mustard and chicken stock, stir and reduce by half.
Add the cream and reduce, until thick, then with season with salt and freshly ground black pepper.
For the beetroot and bacon, place the beetroot into a bowl with the sugar and balsamic vinegar, then season with salt and freshly ground black pepper.
Heat the olive oil in an ovenproof frying pan over a medium heat and add the beetroot mixture. Fry for two minutes, then place into the oven for five minutes.
To serve, place the chicken onto a serving plate and pour over the sauce. Garnish with the crisp pancetta and croutons. Serve the beetroot in a serving bowl to the side.