"This recipe originally came from one of our favorite Food Network stars, Nigella Lawson. A little alteration here and there (like including Idahoan's Original Mashed Potatoes) to this wonderfully rich cake made with Coca-Cola® and a new favorite was created."
Preheat oven to 350 degrees F. Coat the sides and bottom of spring form pan with nonstick cooking spray.
Melt stick of butter in a large, wide sauce pan.
Add cola, cocoa powder and superfine sugar and whisk until smooth. Remove from heat.
Whisk sour cream, eggs and vanilla thoroughly until almost a batter-like consistency and add slowly into the slightly cooled butter mixture.
Add dry Original Mashed Potato flakes and baking soda. Stir thoroughly. The batter will have a slightly grainy appearance but don't be concerned.
Pour into spring form pan and bake for 45 minutes to an hour. Test center of cake with a wooden toothpick (cake is done when the toothpick comes out clean).
Cool and remove from spring form pan. Note: This is a very dark and dense cake.
Frosting: The cream cheese should be at room temperature. Add cream and powdered sugar and mix in a food processor or with a large whisk. Adjust powdered sugar and cream to ensure a nicely thick frosting that is still spreadable.
Frost just the top of the cake once it's unmolded and serve chilled. This cake is even better the next day!