Preheat the oven to 350 F.

Prepare three, 8-inch round cake pans by spraying them with cooking spray or greasing them with shortening, and then coating them with a fine layer of cocoa powder. Set aside. (you can also add a parchment round to the bottom and grease and dust that as well for added easy-release)

In a large mixing bowl, combine the brown sugar, eggs, and butter. Beat well.

Add the cocoa powder.

Slowly add the boiling water while mixing. Blend until smooth.

Add the flour and baking soda. Beat again until smooth.

Add the sour cream. Beat again until smooth.

Divide the batter between the three prepared cake pans.

Bake for 15 minutes or until the toothpick test comes out clean.

Allow cakes to cool for 15 minutes before flipping them out onto your work surface. It may help to run a knife around the edges to release the cake.

Allow cakes to cool completely before frosting.

Cream the butter and confectioner’s sugar together.

Add 2 tablespoons of milk and the vanilla. Beat well. (If the frosting is too thick, add more milk. If it is too thin, add more sugar.)

Place one layer of cake on a serving dish.

Cover with 1/3 of the frosting.

Add another layer of cake on top of that frosting, followed by another layer of frosting.

Add the final layer of cake with the remaining frosting on top.

If desired, top with chopped chocolate bars.