French Pound Cake or Quatre-Quarts

0 Preheat the oven to 350F. butter a 9x5 loaf mold or round mold and coat lightly with flour, or use a no-stick bakery spray.
1 Soften the butter in a bowl until it becomes creamier. Add the sugar 2 to 3 times and whisk vigorously until a nice cream is created.
2 Separate the egg yolk from the white. Add the egg yolks to the butter-sugar mixture. Incorporate the sifted flour.
3 In another bowl, beat the egg whites at full speed with a pinch of salt. Beat until soft peaks form and no white liquid remains in the bowl.
5 Gently fold one-third of the whipped egg whites into the butter mixture to loosen the batter. Add the remaining whites and fold gently from the bottom upward until incorporated. Do not overmix, as you want to preserve as much air as possible.
4 Pour the mixture into the mold and bake for 40 minutes in the middle of the oven.Verify that it is ready by inserting a knife in the middle.Remove from the oven and wait 5 minutes prior to removing from the mold.