What I have for you is one of the best microwave chocolate cakes that I ever tasted. I found this particular recipe when my built-in oven finally died and I was in need of some chocolate cake. This recipe is just as light as a typical packaged cake mix instead of one using all-purpose flour.
Five-Minute Microwave Chocolate Cake
1/4 cup unsweetened cocoa
1/4 teaspoon baking powder
1/4 teaspoon salt
2/3 cup hot water, divided
3/4 cup plus 2 tablespoon flour
1 cup sugar
1/2 teaspoon baking soda
1/4 cup plus 2 tablespoons canola oil
2 teaspoons vanilla
Grease a round 8 x 1-1/2"-inch microwave baking dish. First microwave the cocoa and 1/3 cup of the water on HIGH (full power) for about 40 seconds or until slightly thickened.
Now sift flour, sugar, baking soda, baking powder and salt together in your mixing bowl. Add oil, the other 1/3 cup of hot water, egg, vanilla and the chocolate mixture. Beat this until smooth.
Pour batter into your greased pan. Microwave on HIGH for 5 to 6 minutes or until the cake begins to pull away from the sides of the pan. (It will look moist in some spots, but this will go away once the cake sits.)
Cool, then frost with my Simple Chocolate Frosting.
Simple Chocolate Frosting
1 cup confectioners' sugar
1/8 cup unsweetened cocoa
1/8 cup margarine
1/8 cup milk
1 teaspoon vanilla
Beat everything in your bowl until creamy and spreadable!