1Preheat oven to 400 degrees.Grease and flour a 9 x 13 inch pan.
2In a saucepan,combine margarine,oil,cocoa and water.
Bring to a boil over medium high heat,stirring often.
In a large bowl,sift together the flour and splenda.
Make a well in the center and pour in the cocoa mixture.Stir until smooth.Mix in the chocolate milk,eggs,vanilla extract,ground cinnamon and baking soda.Pour batter into prepared pan.Bake in the preheated oven for 20 minutes.Allow to cool slightly before frosting.
3For the frosting:In a large saucepan,combine margarine,malted milk powder and milk.Bring to a boil,stirring often.Remove from heat.Stir in mint extract,brown sugar and peanut butter.Beat until the frosting is blended.Pour over warm cake,serve with a glass of milk.