- In a mixer, using a whisk, mix the softened butter with the icing sugar. Then, add the eggs, which should be at room temperature, and continue to whisk the mixture. Gradually drizzle in the milk, which should already be brought up to room temperature. Lastly add the baking powder and flour mixture.
- Whip the egg whites to soft peaks and stiffen with the sugar. Add the whisked egg whites to the first mixture.
- Use some of the mixture in the oil and carefully mix it all together with the basic mixture.