Step 1: Prepare the Dough

1. In a medium bowl, whisk together the flour, cocoa powder, baking powder, and salt. Set aside.
2. In a large mixing bowl, beat the granulated sugar, brown sugar, and oil (or melted butter) until smooth.
3. Add the eggs and vanilla extract, mixing until fully incorporated.
4. Gradually add the dry ingredients to the wet ingredients, mixing until a soft dough forms.

Step 2: Chill the Dough

1. Cover the bowl with plastic wrap and chill the dough in the refrigerator for at least 2 hours, or up to overnight. This step is crucial for preventing the cookies from spreading too much.

Step 3: Preheat the Oven

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

Step 4: Shape and Coat

1. Scoop the chilled dough into 1-inch balls (about 1 tablespoon each).
2. Roll each ball generously in powdered sugar, ensuring they are fully coated.
3. Place the coated dough balls 2 inches apart on the prepared baking sheets.

Step 5: Bake

1. Bake the cookies for 10-12 minutes, or until the tops are crackly and the edges are set.
2. Allow the cookies to cool on the baking sheets for 5 minutes before transferring them to a wire rack to cool completely.