Preheat oven to 350 degrees. Mix tofu and vinegar until well blended. Add brown sugar, canola oil and vanilla; blend well again.
Sprinkle flour, cocoa, baking powder and baking soda over top and then blend all together just until combined.
Grease 1 qt. baking pan. (You can find this out by filling your baking pans of any shape with 4 cups of water to measure.) Pour batter into pan.
Bake 40 min. or until toothpick inserted in center comes out clean and cake has pulled away from the side of the pan. Turn upside down on a wire rack. Place baking tray under wire rack and pour frosting over cake while warm. Let cool completely before cutting, at least 30 min.
FROSTING:
Melt chocolate chips until half melted in microwave safe bowl starting at 30 seconds or on double broiler; then place in blender along with the last measurement of silken tofu (on bottom of ingredients list), powdered sugar and milk. Blend all together, adding teaspoons of milk just until frosting has consistency to pour. Set aside until cake is finished baking.