Method

• Pre-heat the oven to 140°C/Fan 120°C/Gas Mark 1. Cover 2-3 large baking trays with foil – or lightly grease them / use baking paper.
• Whisk the egg whites and salt with a stand/electric whisk (or strong arms!) for approx two minutes, starting slowly and building up the speed. You'll see it get white and frothy.
• The egg whites will start to look less frothy and more like a billow of white snow - the 'soft peaks' stage. At this point, put the speed up even faster and slowly pour in the caster sugar until you get firmer meringue 'peaks'.
• Stop whisking and gently fold through the chocolate and walnuts. Dollop teaspoons (no bigger) of the mixture onto the trays – spaced out.
• Place in the oven and bake for 20 minutes at 140°C. Then reduce the heat down to 100°C/Fan 90°C/Gas Mark 1/4 and continue baking for 1 hour 15 minutes. Finally leave in the (turned-off) oven either overnight – or for a further 30 minutes - 1 hour.