Cake Roll: Heat oven to 375. Line jelly roll pan, 15.5x 10.5 x1 inch, with cooking parchment paper, aluminum foil or waxed paper; grease aluminum foil or waxed paper generously. Beat eggs in small bowl with electric mixer on high speed about 5 minutes or until very thick and lemon colored. Pour eggs into medium bowl. Gradually beat in granulated sugar. Beat in water and vanilla on low speed. Gradually add flour, cocoa, baking powder and salt, beating just until batter is smooth. Pour into pan, spreading to corners.
Bake dozen to 15 minutes or until toothpick inserted incenter comes out clean. Immediately loosen cake from edges of pan and invert onto towel generously sprinkled with powdered sugar. Carefully remove paper. Trim off stiff edges of cake if necessary. While hot, carefully roll cake and towel from narrow end. Cool on wire rack at least 3 minutes.