Preheat oven to 350°F (175°C). Line baking sheets with parchment paper.

In a large bowl, whisk together flour, cocoa powder, baking powder, and salt.

In another bowl, combine granulated sugar, vegetable oil, eggs, and vanilla. Mix well.

Gradually add the dry ingredients to the wet ingredients, mixing until combined.

Cover the dough and refrigerate for at least 2 hours.

Shape the dough into 1-inch balls and roll them in powdered sugar.

Place cookies on the prepared baking sheets, spacing about 2 inches apart.

Bake for 20 minutes, until the cracks form on the surface.

Remove from oven and let cool on wire racks before serving.