Fill a medium-sized saucepan halfway with water. Place on the heat, then place smaller saucepan inside. The smaller pot should float. Add the butter to the smaller saucepan and let it melt without burning. Remove from the heat and let cool.
While the butter cools, place the eggs, egg yolks and sugar in a small saucepan. Cook in a bain marie, as you did with the butter, whisking as you work.
Once the sugar has melted and the mixture is warm, remove the saucepan from the heat and beat with an electric whisk or mixer for about 10 minutes.
Once the batter is airy, add the grated lemon peel. Then add the sifted flour and starch, stirring with a spatula. Also add the vanilla.
Margherita Cake - Step 3
Add the butter to a small part of the batter, then incorporate this back into the rest of the batter using a whisk. Grease a round cake pan and line with a sheet of parchment paper. Pour the batter into the pan and fill 2/3rds of the pan.
Bake in a 375°F oven for about 30 minutes. Once done baking, remove the cake from the oven and let cool. Transfer onto a serving dish and garnish with powdered sugar.