Wash and peel parsnips, potatoes and apples. Cut into large pieces and place in cold water with lemon juice.
Peel and finely dice shallots. Heat butter in a saucepan, shallots over medium heat
Steam until glassy. Drain the parsnips, potatoes and apples, add, sauté briefly, deglaze with white wine and reduce by half. Top up with broth, bring to the boil and lightly for 25 minutes
Simmer. Puree the soup, add the cream and season to taste.