Combine the flour, sugar, cocoa powder, baking soda, and salt in an 8x8 inch pan. Whisk to combine.
Make 3 wells in the flour mixture. Pour the oil into one well, the vinegar into another well, and the vanilla into another well. Pour the water over everything.
Whisk the mixture until a cake batter forms. You may need to use a spatula on the corners of the pan to make sure all of the dry ingredients get mixed in.
Bake for 30–35 minutes, or until a toothpick inserted into the center comes out clean.
Let cool, slice, and serve. You can top the cake with powdered sugar, whipped cream, or your favorite chocolate frosting.
Notes
Wacky Cake can be stored at room temperature or in the refrigerator. It can also be frozen for up to 3 months (wrap in plastic wrap first, then place in a resealable freezer bag). You can use one cup of brewed coffee (room temperature or chilled) in place of the water. You can also substitute apple cider vinegar for the white vinegar.Don't want to mix it in the baking dish? Use a mixing bowl instead, then pour it into the dish.