In a stand mixer with a paddle attachment, mix together the flour, cocoa powder, salt, sugar, and baking powder.
On medium speed, add the butter and mix until the mixture resembles wet sand.
Add the milk and mix until the mixture forms a ball dough. Wrap with plastic wrap and refrigerate for 30 minutes.
Preheat the oven to 350F. Prepare a baking sheet with a sheet of parchment. Set aside.
On a lightly floured surface, role the dough out until it's 1/8" thin. Punch out circles with a round cookie cutter and transfer to the baking sheet.
Bake for 15 minutes or until crispy and lightly golden. Let cool.
In a microwave or double boiler, melt the dark chocolate. Drizzle the cookies with the chocolate and while still melted, top the chocolate with cocoa nibs.