Empty the Greek yogurt container into a large mixing bowl. Using the container as your measuring device, add 1 yogurt container full of sugar and 1 yogurt container full of canola oil to the bowl.
Add two large eggs. Using an electric hand mixer, beat mixture until smooth.
Add your dry ingredients still using the empty yogurt container. Add 2 container-fulls of self-rising flour and 1 full container of cocoa powder. Beat on a low speed until lump free, and slowly add in a full container of warm water (or coffee) and a pinch of salt. Mix until smooth.
Once smooth, pour the batter into a prepared 10-inch spring-form pan. Bake for 35 minutes or until a toothpick, when inserted into the middle of the cake, comes out clean. Let cool.
Release the cake from the spring form pan and dust with powdered sugar, if desired.