Two minutes in the microwave, and out pops a personal chocolate cake.
In a ceramic mug (specifically one slightly larger than the cake you want), mix the flour, sugar, cocoa powder, baking soda, and salt, then stir in the milk along with the canola oil, water, and vanilla extract.
Throw that mug in the microwave and nuke it for around 1 minute, 45 seconds. You want to make sure the cake is done in the middle.
The cake will expand as it's cooking in the microwave, which is why you want to use a mug that's a little oversized. Otherwise, it'll spill all over the place.
If you'd like a slightly healthier version of this cake, use 1 1/2 tablespoons of plain unsweetened applesauce and 3 tablespoons plus 1 teaspoon water instead of the milk.