Pre-heat the oven to 350°.
Cream (or mix) the butter and sugar together.
Then add the eggs and vanilla, mixing well.
Whisk or sift all the dry ingredients, including the flour, baking powder, cocoa powder, and salt, together.
Mix the dry ingredients into the creamed mixture alternately with the milk, beginning and ending with the dry ingredients. If the batter is too thin, you may need to add just a bit more flour.
Drop from teaspoons onto a baking sheet.
Bake at 350° for 10 to 12 minutes.
When fully baked, remove the cookies from the cookie sheet, and allow them to cool on a wire rack.