01 -
Preheat the oven to 175°C and grease a 23x23-centimeter baking dish.
02 -
In a large mixing bowl, whisk together granulated sugar and melted unsalted butter for about 1 minute until the mixture is light and aerated.
03 -
Incorporate eggs one at a time, mixing thoroughly after each addition, then blend in the vanilla extract.
04 -
In a separate bowl, sift together cake flour, baking powder, and salt. Gradually add the dry mixture to the wet ingredients, stirring until just combined.
05 -
Gently fold sour cream into the batter until fully integrated and smooth.
06 -
Pour the batter evenly into the prepared baking dish. Sprinkle the top uniformly with granulated sugar.
07 -
Bake for 30 to 35 minutes, or until a inserted toothpick emerges clean.
08 -
Allow to cool slightly before slicing into portions and serving.