Preheat the oven to 180C
Beat the eggs and the sugar together.
Sift the flour, salt and baking powder together into a bowl. I don't usually sift flour, most modern flour doesn't have lumps but I did in this case because I wanted a light texture.
Mix the egg/sugar and flour mix together.
Place the mixture into a piping bag.
Pipe 6cm or 4 inch lines of the batter, with 4cm/2 inch separating them. The batter spreads so make sure there are gaps.
Sprinkle, with a tea strainer or small sieve, extra caster sugar all over the piped biscuits. This will give the characteristic sugary top.
Leave to settle for a few minutes then bake for 10 to 15 minutes, or until golden, checking regularly.
Leave to cool, then peel the biscuits off the silpat.