Polish Babka Cake
1 tablespoon almond extract 1 teaspoon vanilla sugar 1 ¼ cups all-purpose flour 1 ½ cups confectioners' sugar 1 ½ tablespoons butter 2 tablespoons raisins 2 tablespoons unsalted butter, at room temper… 2 teaspoons baking powder 3 tablespoons dried bread crumbs 3 tablespoons sour cream, or more to taste 4 eggs, separated ½ lemon, zested and juiced ¾ cup potato starch ¾ cup unsalted butter, at room temperature