Prepare the almonds and butter by leaving them at room temperature.
In a bowl, cream the butter and sugar together.
Add the egg and mix well.
Sift the cake flour, almond flour, and baking powder, then add to the mixture and combine.
Mix the sliced almonds into the dough.
Divide the dough into 6 portions and shape into balls.
Bake in a preheated oven at 180°C (356°F) for 15 minutes.