Cream the butter until soft, then mix in the powdered sugar.

Add the egg yolk and vanilla extract, and mix well.

Sift the cake flour and cocoa powder, then fold them into the mixture.

Add the sliced almonds and gently mix them into the dough.

Knead the dough lightly until it forms a cohesive ball.

Place the dough into a biscuit mold and freeze for 1 hour.

Remove the dough from the freezer and slice it into 1cm thick pieces.

Place the slices on a baking sheet lined with Teflon paper.

Bake at 180°C for 15 minutes. Adjust time and temperature based on your oven.

Let the cookies cool on the baking sheet for 5 minutes, then transfer to a wire rack to cool completely.