Preheat oven to 400° F. Oil a Sheet Pan Liner and place on a Sheet Pan.
In an electric mixer, whisk eggs and sugar on high for 5 min, until pale, thick, and doubled in volume.
Add water, vegetable oil, and vanilla. Sift in flour, cocoa, and baking powder, and fold very gently so that you do not lose any of the airy volume.
Pour batter carefully onto Sheet Pan Liner, spreading batter to all edges. Bake 10–12 min until golden brown.
To shape cake roll: while still warm, spread cake with Chocolate Truffle Dip. Using the Sheet Pan Liner as a guide, starting at the short end, gently loosen cake while rolling snugly into shape. Sit the cake seam-side down.
Slice into portions with a bread knife or chill until ready to serve.