Insta-Cake | MetaFilter
"Preheat oven to 350 degrees F.

Mix dry ingredients in a nonstick 8 x 8 pan or a loaf pan:
* 1 1/2 cups all purpose flour (no fancy cake flour needed)
* 3/4 cup sugar (sweet but not cloying)
* 3 tablespoons cocoa powder
* 1/2 teaspoon salt
* 1 teaspoon baking soda
* Additional spices to taste: try 1/2 teaspoon each of ginger, cinnamon, and nutmeg to start

Add wet ingredients: stir into dry ingredients in the following order with a fork until combined, but do not overmix
* 3 tablespoons oil (the original used 4 T, and I've seen as high as 6 T, but 3 works just fine)
* 1 tablespoon white vinegar
* 1 cup cold water with 1 teaspoon vanilla added (you might also add 1 teaspoon of peppermint or almond extract)

Put into oven for 30 minutes for an 8 x 8 pan, or 40 minutes for a loaf pan. Cake is done when it pulls slightly away from the sides and/or a toothpick inserted in the center comes out clean."

I've seen a few other "Wacky Cake" recipes, but this one has the least sugar and I can assure you it will produce one of the best tasting chocolate cakes you have ever tried. Icing is superfluous it is THAT good. And when I made it, I did not have a non-stick pan so I spread some oil in a glass pan and mixed the dry ingredients in a mixing bowl, then poured the wet ingredients into the same bowl in the proscribed order, mixed together with a fork until combined, then poured into the glass pan. Baked for exactly 30 minutes. Great recipe.