Preheat your oven to 350 degrees F.

Line two 9" round cake pans with parchment paper. Grease the paper. Set aside. (see note for a tip)

In a medium mixing bowl, whisk together the dry ingredients (flour, sugar, soda, salt and cocoa).

In another mixing bowl, whisk together the wet ingredients (oil, water, vanilla and vinegar).

Add dry ingredients to wet ingredients and whisk together until smooth.

Pour the batter into prepared pans.

Bake for 25 to 30 minutes, or until the toothpick inserted into few place in the cake comes out clean. (Out of toothpicks? Use an uncooked spaghetti noodle!) Rotate pans half time through baking.

Cool completely before frosting.

In a double boiler, melt butter. Add chopped chocolate as soon as the butter is melted. Stir often until the chocolate is melted. Set aside to cool to room temperature.

Add corn syrup and vanilla to the melted chocolate. Mix in well.

Using a hand held electric mixer, mix in the sour cream. The frosting will be light in color.

Sift 1 cup of powdered sugar at a time, right over the bowl with frosting.

Mix in well.

Add siften cocoa powder. Mix in well.

Add cream if the frosting seems too stiff.

Frost the cake.

Place 1st layer on a serving plate. Scoop two ice cream scoops of frosting on top of the layer and spread evenly with an offset spatula.

Repeat for all layers. To make it easier, make sure you always frost the smooth side of the layer.

When the last layer of the cake has been placed on top and frosted with three scoops of frosting, use the remaining frosting to cover the sides of the cake.

Make decorative swirls with the back of a spoon.

Let set before cutting.