Whisk together the flour, salt and baking powder in a small bowl and set aside.
2. Using a stand or hand held mixer, cream the butter and sugars together until light and fluffy, 2-3 minutes.
Add in the eggs one at a time, mixing well after each addition. Then add in the vanilla and cocoa powder and mix well, stopping to scrape down the sides when needed. Slowly add in the flour mixture, and mix until smooth.
Shape the dough into two discs and wrap in plastic and chill for at least two hours up to overnight.
5. When ready to bake remove the dough from the refrigerator and preheat the oven to 325 Deg F. Line baking sheets with parchment or silicone bake mats.
6. Sprinkle cocoa powder onto a counter and roll out one of the discs to ⅛” thick. (You can also roll the dough on a silicone bake mat or between two sheets of wax paper) cut out using linzer cutters making sure you have equal amount bottom cookies as you do top ones with the center cut out and place on the prepared cookie sheets at least 1-inch apart.
Bake for about 9 minutes until the edges are firm and the centers are slightly soft and puffed. Let cool on cookie sheets 2-3 minutes then transfer to a wire rack to cool completely