Refrigerate the dough for 10-15 minutes (this additional step will make it easier to roll the dough into balls and yield nice puffy cookies).
Use 2 fingertips to gently pat the dough into a ball as you roll the dough in powdered sugar.
Place the dough balls approximately 2 inches apart from each other on the baking sheets and repeat.
I often bake a double batch of this recipe and left a little note in my cookbook with the following measurements (double batch):
1/2 cup confectioners' sugar
3 1/3 cup all purpose flour
1 cup unsweetened cocoa powder
1 tablespoon baking powder
1/2 teaspoon salt
2 cup sugar (granulated)
1 cup unsalted butter (2 sticks) at room temperature
4 large eggs
1 teaspoon vanilla extract