To make lady fingers, beat the yolks of 5 large room-temperature eggs until their color shifts to a pale yellow, and slowly add 9 tablespoons and 1/2 teaspoon of white sugar to the yolks while beating. Continue beating at medium speed until the mixture triples in volume. Sprinkle 7/8 cup of flour onto the fluffy egg mixture. Stir lightly to combine the ingredients, but do not over-mix them.
In another bowl, beat the 5 egg whites briskly until soft peaks form. Add 1 1/2 tablespoons of sugar, and continue beating until stiff peaks form. Add 1/3 of the egg whites to the egg yolk mixture, and lightly stir to combine them. Fold in the remaining egg whites carefully, trying to maintain as much volume as possible.
Place the lady finger batter into a pastry bag. Pipe 24 to 32 3.5-inch lady fingers onto a baking sheet covered with parchment paper. Sprinkle the lady fingers with confectioner's sugar.
Bake the lady fingers for 14 to 16 minutes on the middle rack of an oven preheated to 350 degrees Fahrenheit. Remove the lady fingers from the oven once they spring back when touched. Cool them on the baking sheet before storing them in a sealed container.