Preheat oven to 180°C/350°F/Gas 4
Wrap the beetroots in foil and bake in the oven for 50-60 minutes until tender when pierced with a skewer.
Meanwhile place the Piccolo parsnips and pears on a baking sheet, brush with the oil and sprinkle with sea salt and black pepper and the thyme sprigs. Roast for 20 minutes or until the Piccolo parsnips and pears are lightly browned and tender, leave to cool. Peel the beetroots when they are cool and cut in half.
For the walnuts, place the water and sugar in a pan and bring to the boil. Cook for 5 minutes or until thickened to a syrup, add the walnuts and stir for 30 seconds. Drain off the liquid and set aside.
Combine the dressing ingredients together and season to taste.
To assemble the salad, divide the watercress onto 4 plates, top with the roasted Piccolo parsnips, pears, beetroot and blue cheese and drizzle over the dressing and finally top with the candied walnuts.