Sift together the flour, cocoa powder, baking powder, and salt (if using). Set aside

Cream together the butter and sugar until light and fluffy.

Add the egg and vanilla, mixing completely.

Slowly add the flour mixture beat until thoroughly incorporated.

On a piece of parchment or waxed paper, place the dough and flatten into a disk. Wrap with the paper completely.

Chill for at least 1/2 hour. Longer is okay.

Grease a baking sheet or line it with parchment paper.

On a lightly floured board, roll the dough out to about 1/4 inch thickness.

Cut into desired shapes and place on prepared baking sheet about 2" apart.

Bake 15-20 minutes.

Cool completely on wire racks before decorating as desired.