- Combine flour, baking powder, baking soda and salt in small bowl.
- Mix together granulated sugar, cocoa and 1/3 cup boiling water in large mixing bowl with wooden spoon. Add oil, eggs and vanilla; beat lightly until just combined.
- Alternately add flour mixture and soymilk, beating after each addition.
- Pour batter into nonstick 15 x 10-inch jelly roll baking pan.
- Bake in preheated 350°F oven 18 minutes, or until wooden toothpick inserted near the center comes out clean.
- Cool completely on wire rack.
- Dust with powdered sugar, if desired.