Whisk the egg whites in a separate bowl until you get a light foam. Tip this into the dry ingredients with the melted butter and gently stir together. Divide the batter between the friand holes, then, working quickly, top each with a spoonful of the ricotta mixture. Add a slice of peach to the top of each, a sprinkling of chopped pistachios, and a dusting of icing sugar. Bake for 20-23 minutes until they have risen and are golden – if you check with a skewer you’ll probably hit the molten ricotta, so check round the edges instead.