Step by Step

• Preheat your oven to 350°F (175°C). Line a 10×15-inch jelly roll pan with parchment paper and lightly grease it.
• Whisk together the flour, cocoa powder, baking powder, and salt in a medium bowl.
• Beat the eggs with granulated sugar in a large bowl until pale, thick, and doubled in volume.
• Mix in the milk and vanilla extract gently until fully combined.
• Sift the dry mixture into the wet mixture and fold gently with a spatula.
• Spread the batter evenly into the prepared pan. Bake for 10–12 minutes.
• Turn out the warm cake onto a powdered-sugar-dusted towel and roll it with the towel inside. Let it cool completely.