Steps for preparing and baking the margherita cake:

• Melt the butter over low heat or in the microwave and let it cool slightly.

  In the stand mixer, place whole eggs and sugar and start whisking them, when you see the mixture starting to combine, add the salt and the orange zest, whip the mixture for 8 minutes at maximum speed.

  Then, with the mixer still running, add the egg yolks one at a time, do not add the next one until the previous one is well blended into the mixture.

• In a large bowl, sift the flour, potato starch, and baking powder twice to get a very light and lump-free mixture.

  Set the mixer to medium speed and add the dry ingredients all at once, then increase the speed of the mixer, when you achieve a homogeneous mixture, turn off the mixer.

• Take a part of the batter, put it in a bowl, add the melted butter and mix quickly with a spatula, add a few more spoonfuls of the batter from the mixer and work it well.

  Transfer the mixture to the mixer and with movements from bottom to top, incorporate it into the remaining batter.

  Pour the mixture into a previously buttered and floured 8-inch diameter mold, bake in a preheated static oven at 374°F for 40 minutes.

  Take the cake out of the oven (always do the toothpick test for safety), let it cool, remove it from the pan, and dust it with powdered sugar.