This hot fudge cake recipe really satisfies my chocolate craving, too.  
 It is very sweet however.
 Hot fudge cake
 1 cup flour
 3/4 c sugar
 6 tbls baking cocoa, divided
 1/4 tsp salt
 1/2 c skim milk
 1 tsp vanilla
 1 c packed brown sugar
 1 3/4 c hot water
 In a medium bowl, combine flour, sugar, 2 Tbls cocoa, baking powder and 
 salt.  Stir in the milk and vanilla until smooth.  Spread in aan 
 ungreased 9-in square baking pan.  Combine brown sugar and remaining 
 cocoa; sprinkle over batter.  Pour hot water over all; do not stir.  Bake 
 at 350 degrees for 35-40 minutes.  Serve warm.  I like to serve it with 
 frozen non-fat vanilla yogurt.  Yield: 9 servings.