Combine the flour, salt, cocoa, powdered sugar, and baking powder in the bowl of an electric mixer fitted with the paddle attachment. Give it a slow mix.
Add the butter and stir until pea sized clumps are formed in the dry ingredients.
In a separate bowl mix the honey and milk until the honey dissolves. Stir into the dry ingredients until a dough forms. Split dough into two equal parts.
Cut a size of parchment to the size of a cookie sheet (or use a silicone mat). Place one half of the dough directly in the center of the parchment and roll out into a large rectangle, about 1/8-1/4 inch thickness.
Prick the top of the dough with a fork to prevent bubbling.
Place the baking tray into the oven and bake for 12-15 minutes, or until the edges slightly curl up and the middle looks like it has set.
Carefully transfer the cookie slab onto a cutting board and immediately cut into squares or desired shape. Make sure you do this while they are warm as they will crisp up fairly quickly as they cool.