In a medium bowl, whisk together the flour, cocoa powder, baking powder, and salt. Set aside.

In a large bowl, using an electric mixer, cream the butter and granulated sugar together until light and fluffy, about 2 minutes.

Add the eggs, one at a time, beating well after each addition. Stir in the vanilla extract.

Gradually add the dry ingredients to the butter mixture, mixing until just blended.

Cover the bowl with plastic wrap and refrigerate the dough for at least 2 hours, or until firm.

Preheat the oven to 350°F (180°C).

Using a medium cookie scoop, form the dough into balls, about 1 tablespoon each.

Roll each ball in the powdered sugar until completely coated.

Place the balls on the prepared baking sheet, spacing them about 2 inches apart.

Bake for 12 to 14 minutes or until the cookies are set.

Let the cookies cool on the baking sheet for 5 minutes, then transfer them to a wire rack to cool completely.