In a medium bowl, combine the flour, cocoa, salt, and baking soda.

In the bowl of a stand mixer, cream the butter with both sugars using the paddle attachment. Reconstitute the peanut powder with the water and add it to the butter mixture. Mix until incorporated. Add the vanilla and egg. Mix well.

Add the dry ingredients into the wet ingredients all at once and mix until incorporated. Test dough for stickiness with finger and add an extra ¼ cup flour if needed. Roll dough into a log and cut 16 equal pieces.

For the Peanut Butter Filling: Stir the ingredients in a small bowl until a dough forms. Roll the dough into a log and cut 16 equal pieces.

Press one piece of chocolate dough into a flat circle. Press a piece of peanut butter dough flat and place it in the center of the chocolate dough. Wrap the chocolate dough around the peanut butter dough and pinch the seams. Re-flatten the cookie until about ½-inch thick and coat the top and sides of the cookie in granulated sugar. Place cookie on a silicone lined baking sheet. Repeat with remaining pieces of dough placing cookies 1-inch apart.

Bake at 350 degrees Fahrenheit for 8 to 9 minutes until dough starts to crack on the edges. Allow to cool sightly before removing from baking sheet.