These little coffee cakes are light delicate and delicious. With only three components they may look simple to make but timing is crucial; you must wait until the coffee icing is the exact temperature that it runs over the sponge covering evenly. Too hot and it will slide straight off, too cold and you will be left with a mountain of icing on the top of the sponge. Equally the French buttercream is all in the timing, the sugar must reach an exact temperature of 121°C to set to the correct consistency, this is called ‘soft ball’ in sugar work.
If you do not have a sugar thermometer you can do the cold water test. Fill a small glass or bowl with cold water, once the sugar has been boiling for three or four minutes and the bubbles have gotten smaller quickly dip your fingers into the cold water then dip them into the pan and pinch a little of the sugar, then straight back into the cold water. The sugar should form a pliable ball between your fingers. Too cold and it will dissolve into the water, too hot and it will form a hard ball. Please be careful when doing this, as long as it is done quickly you will not burn your fingers!