Preheat oven to 375 degrees Fahrenheit. Also line the raised centre of an 8 inch flan mould with parchment paper, and grease it with butter.
Break two eggs in a medium size mixing bowl and add 50 grams of caster sugar to them.
Place the bowl in a wide pan containing hot water and beat the eggs well using an electric beater or a hand whisk.
Beat the eggs for 3 to 4 minutes or until the egg and sugar mixture is thick and a bit sticky.
Once your eggs have been properly beaten, add flour to the bowl and fold it gently using a wooden or metal spoon.
After the flour has been completely mixed, and there are no lumps remaining, transfer the mixture to the already prepared flan mould.
Place the mould in the oven preheated at 375 degrees Fahrenheit and bake for 15 to 20 minutes, or until it rises properly.
Let the sponge cool slightly in the mould and then transfer it to the wire rack.
Remove the parchment paper and leave it to cool before you use it.