Separate the Egg (5). You will need 5 egg whites and 4 egg yolks. Set aside.
Put Egg Whites and Caster Sugar (2/3 cup) in a mixing bowl, beat it up until it's foamy. Then turn up the speed and keep beating it until we have stiff peaks.
Take another bowl and add the Egg Yolks, Vanilla Extract (1 teaspoon), and the rest of sugar. Beat it together until it's pale and yellow. Gently fold in half of the egg white. Sift All-Purpose Flour (1 cup) and Baking Powder (1/2 teaspoon) into the bowl. Fold in with rest of the egg whites.
Spoon the mixture into a zip loc bag and snip off one corner. Take a baking tray lined with some non-stick baking paper. Pipe fingers onto the tray. Preheat the oven 180 degrees C (350 degrees F) and cook for 7 or 8 minutes just until they are lightly golden around the edges. Cool on the tray for 15 minutes then transfer them to a wire rack.