Roughly chop the nuts (eg, hazelnuts, walnuts, macadamia, almonds, pecans). Toast in a dry pan on a high heat for 3 minutes. Meanwhile, line a baking tray with baking paper. Put the sugar and 25ml water into a large pan, heat gently until the sugar dissolves, then turn up to high. When the mixture starts to bubble and go golden, add the nuts and stir. Once the sugar and nuts are a dark golden caramel, pour on to the tray and spread thinly with a knife (be quick as it sets fast). Leave to cool then crush.