Cream the butter and sugar until light and fluffy. 

Add in egg, mix well. Then sift in flour, cocoa powder and salt, mix until well-combine. Add in almond slices, mix together. 

Wrap it with cling film, shape it to a log. Freeze for 45 minutes. (if the dough is too loosen, add some milk) 

Slice it into 1cm thick pieces, place it on parchment paper. Pop in preheated oven at 180C, bake for 15 -20 minutes. .Enjoy!