Beat the eggs in the sugar, add the oil and yoghurt. Once they're beaten well, add the flour (I always sift it) with the baking powder.
Grate the wafers and stir carefully with a wooden spoon.
Pour it into a cake form and bake at 356°F (180 °C) until ready.
Once ready, you can sprinkle it with powdered sugar.
You don't have to use a cake form, a tray also works.