In the bowl of a stand mixer, add the sugar, cocoa, and oil, and beat to combine. Add the eggs, one at a time, beating until smooth. Stir in the vanilla extract.

In a separate bowl, combine the flour, baking powder, instant espresso powder, and salt.

Gradually stir the dry ingredients into the bowl with the wet ingredients until just combined. Cover the dough, and refrigerate for at least 4 hours or up to overnight.

When ready to bake, preheat the oven to 350 degrees F. Line two baking sheets with parchment paper or aluminum foil.Using a small ice cream school, portion the chilled dough into 1-inch balls.

Roll each ball in powdered sugar, and place them on the cookie sheets 1 inch apart on the prepared cookie sheets.

Bake on the center rack for 10-11 minutes or until the edges begin to crinkle. Ours took exactly 10 minutes! Be careful not to overbake. Note: the cookies will continue to bake on the cookie sheet once removed from the oven. Let them stanad for a few minutes before transferring them to a wire rack to cool completely.

Store at room temperature for up to 1 week.