1 Peel carrot and finely chop. Finely chop the white part of the leek, rinse well and drain. Rinse chicken breast and pat dry. Cut into large pieces and grind in a meat grinder (or finely chop in a food processor).
2 Separate the eggs (reserve 1 yolk for another use). In a bowl, combine egg whites, chicken, diced vegetables and 125 ml (approximately 1/2 cup) water. Stir to combine.
3 Transfer chicken mixture to a pot. Add the cold chicken stock and stir well.
4 Bring the mixture to a simmer over medium heat, stirring frequently. Stop stirring and cook over very low heat until the chicken mixture coagulates and floats to the top of the stock, about 2 hours. (Do not return to a boil, which will make the broth cloudy.)
5 To make the gnocchi, remove seeds from pumpkin and cut into wedges, about 3 cm (approximately 1 1/4 inch) thick. Place wedges, skin side down, on a baking sheet. Roast on the middle rack of preheated oven at 200°C (fan 180°C, gas: mark 3) approximately 400°F) until tender, about 30 minutes.
6 Remove pumpkin slices from the oven and peel. Press pumpkin flesh through a potato ricer into a bowl. Season with salt and pepper and a pinch of freshly grated nutmeg. Add egg yolk and flour and knead into a smooth dough.
7 Roll out dough on a floured work surface and cut into 1 cm (approximately 1/2-inch) pieces.
8 Peel parsnips and cut into very thin strips.
9 Cook the gnocchi in a pot of boiling salted water until they float to the top, about 3 minutes, adding parsnips after 2 minutes. Drain gnocchi and parsnips, rinse with cold water and drain well.
10 Line a sieve with cheesecloth or paper towels. Rinse parsley and chervil and shake dry. Reserve some chervil for garnish and place the remaining herbs in the sieve. Carefully pour the broth through the sieve into another pot. Discard the chicken-vegetable "raft" from the broth. Heat gnocchi and parsnips in the consommé over low heat. Serve in soup bowls or deep plates, garnished with chervil.