Place the sugar in a pan along with all the other ingredients up to and including the pistachios, simmer over a low heat for approx. 3 mins., stirring constantly. Add the flour, mix. Using two wet teaspoons, shape approx. 1/3 of the dough into approx. 10 small mounds, place on a baking tray lined with baking paper – ensuring they are well spaced out.
Approx. 6 mins. per tray in the centre of an oven preheated to 200°C. Remove from the oven, immediately shape the runny florentines into circles using a cutter (approx. 5 cm in diameter). Slide the biscuits and baking paper onto a cooling rack, leave to cool. Bake and shape the remaining biscuits in the same way.
Pour the cake icing into a small bowl. Dip the florentines halfway into the icing, allow the excess to drip off, sprinkle with a little fleur de sel, leave to dry on the baking paper.