Preheat your oven to 350 degrees. Line a baking sheet with aluminum foil or parchment paper. Set aside.
In a large mixing bowl whisk together the flour, cocoa and baking powder. Set aside.
In the bowl of a stand mixer fitted with the paddle attachment combine the butter, sugar and vanilla. Mix on medium speed until the butter is fluffy, about 5 minutes. Beat in the eggs one at a time until fully incorporated. Little by little add in the dry ingredients until just absorbed. Do not over mix.
Wet your hands and roll out tablespoon sized balls of dough and place them 2 inches apart on your baking sheets. Bake for 12 minutes. Cool before frosting.
To make the Glaze:
In a bowl whisk together the sugar, cocoa, vanilla and milk until smooth. For thicker glaze add more confectioners sugar. For thinner glaze add more milk. Spoon over the cooled cookies and decorate with sprinkles.