1. Preheat oven to 350 degrees F. Spray a 13x9" metal cake pan with cooking spray. In a large bowl, combine the flour, cocoa powder, sugar, salt, and baking soda together.
2. Make a large hole in the middle of the mix and add the coffee, canola oil, vanilla extract, and white vinegar into the hole.
3. Mix the ingredients together until it makes a smooth batter. Pour the batter into the cake pan and bake 35-40 minutes, or when an inserted toothpick comes out clean.
Source of recipe: This recipe is for when I have large parties, or I want to make a huge birthday cake design for family/friends.