Wafer Batter

Set the oven at very hot, 450°F/230°C. Whisk 4 egg whites in a bowl just until mixed. Sift in 1 ¼ cups/150 g flour and 1 cup/200 g confectioners’ sugar until combined. Add 5 tbsp/75 g butter, melted and cooled, and 2 tbsp heavy cream.