Firstly, cut carrots and parsnips into matchstick-thin strips. Then blanch in a large saucepan of boiling salted water for 2 minutes. Drain.
Melt the butter in the saucepan. Add the ginger and cook gently, stirring for 2-3 minutes. Add the parsnips, tossing to coat in the butter. Add salt and pepper to taste, then turn the mixture into a large, shallow ovenproof dish.
Pour the creme fraiche over the parsnip mixture and bake in a preheated oven at 190C for 10-15 minutes, until tender. Serve at once.