In a medium bowl, whisk together the granulated sugar, vegetable oil, eggs, and vanilla extract until glossy and smooth.

In a separate bowl, whisk together the all-purpose flour, unsweetened cocoa powder, baking powder, and salt. Fold the dry ingredients into the wet mixture using a spatula just until no flour streaks remain.

Cover the dough tightly with plastic wrap and refrigerate for at least 2 hours (or up to 24 hours) until fully chilled and firm.

Preheat your oven to 177 °C (175 °C) and line two large baking sheets with parchment paper. Place powdered sugar in a small, shallow bowl.

Scoop tablespoons of dough and roll them into 1-inch smooth balls. Generously coat each ball in powdered sugar until completely covered and place them 2 inches apart on the baking sheets.

Bake for 10 to 12 minutes until the edges are set and the tops are cracked. The centers should still look slightly soft. Cool on the pan for 5 minutes before transferring to a wire rack.