Heat the sugar in a light coloured frying pan over a medium heat until it melts. This is quite a slow process, don't rush it.
Meanwhile place the nuts in a single layer across a silpat mat.
Once the sugar is clearly melted and golden, stir a little until the toffee turns a deep brown. Work quickly to scrape this onto the nuts. Sprinkle with salt flakes immediately. Allow to cooled completely.
Break into pieces and place into the Thermomix bowl. Chop for a few seconds to make your crumb. Store in an airtight container in the fridge indefinitely.
Use as a garnish on all desserts that need some crunch!