Cream the butter until soft.

Add sugar and whip until the mixture turns ivory-colored.

Mix in the egg and vanilla extract.

Sift together cake flour, cocoa powder, baking powder, and salt, then fold into the mixture until no dry flour is visible.

Form the dough into one cohesive ball.

Cover the dough with plastic wrap and refrigerate for 30 minutes to 1 hour.

Divide the dough into 15g portions and roll each into a ball.

Roll the balls in sugar, then coat them in powdered sugar.

Bake at 180°C for 10-12 minutes. Adjust time and temperature based on your oven.

Let the cookies cool on the baking tray for 3 minutes, then transfer to a wire rack to cool completely.