Parsnip and Mushroom Souffle

Don't be scared of soufflés. You can ill-treat them as much as you like. It is only at the point of final cooking that you must be precise and serve them immediately. Peel and chop 1lb (375g) parsnips and boil until soft. Reserve cooking water, and purée the parsnips. Cook some chopped mushrooms in butter until soft. Melt 2oz (60g) butter in a pan, stir in 2oz/50g flour, and make into a thick sauce with about 1/2pt/150ml cooking liquor. Stir in parsnip purée and mushrooms. Separate 4 eggs. Stir egg yolks into parsnip mixture carefully off the heat. Season with salt, pepper and chopped parsley or a few leaves of thyme. Whip egg whites into stiff peaks. Fold in with a metal spoon, trying hard not to knock out the air. A few white lumps don't matter. Grease a soufflé dish, and heat the oven to Gas 4/180C, with a metal tray inside to heat the bottom of the dish. Cook for 30 minutes. You can make the parsnip mixture well in advance, and stir in the egg whites at the last minute for convenience, say for a party.