I give you my recipe for sponges biscuits :

• 3 eggs
• 100g caster sugar
• 100 gr flour
• 1 pinch of salt

Using an electric mixer, or in the bowl of your food, turn up the egg whites rather firm.
Add powdered sugar gradually while continuing to to whip.
Add yolks, always with the whip at low speed.
Finally, add the flour and salt and continue to whisk gently until smooth.
Butter a medium size pan, that will allow you to cut your biscuit slices.
Bake for ten minutes in a preheated oven at 180°.
It's so good ! !
Sorry I did not vegan recipe!