These are irresistible, rather like thin, light brownies; the crisp top becomes slightly gooey underneath. For a more firmly crisp result, bake for a further 5 minutes. Use chocolate with at least 50 per cent cocoa solids.
Butter a Swiss roll tin, approximately
In a heavy saucepan, melt the butter and chocolate over the lowest possible heat; do not allow it to bubble. Stir with a wooden spoon until smooth, then add the instant coffee and stir to dissolve. Remove from the heat and stir in the sugar and vanilla essence. Add the whisked egg and mix thoroughly. Sift in the flour and salt and mix until smooth. Pour into the prepared tin and spread evenly. Sprinkle the chopped walnuts all over.
© 1997 Josceline Dimbleby. All rights reserved.