Sift together the baking powder, baking soda, salt (if using), cocoa powder and 5 cups of the flour.
In a separate bowl, cream the butter and sugar with an electric mixer (use the paddle attachment if using a stand mixer) until light and fluffy.
Add the eggs, one at a time, beating well after each addition.
Add the extracts and Greek Yogurt and mix until well-blended.
Gradually add the flour mixture, a cup at a time and mix until well-combined. Do not overmix!
If the dough seems too wet, add up to the remaining cup of flour, ¼ cup at a time (I found I needed ½ cup)
Divide the dough in to 3 balls, wrap each ball in plastic wrap and flatten in to a disc. Chill in the refrigerator for at least 4 hours.
Preheat the oven to 425F. Line a cookie sheet with parchment paper.
Dust a cutting board with cocoa powder.
Unwrap disc and roll the cookie dough to just under ¼" thickness.
Using a round 2" cookie cutter, cut out circles and place them on the parchment-lined cookie sheet.
Bake for 7 minutes. Remove from oven and immediately transfer cookie to a wire rack
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