Just wondering how much addn'l to charge using chocolate ganache on a cake as frosting and a filling for a 2-layered cake.....
Why would you charge any different than any other frostings/icings?
Its no different and easier to make than a Buttercream.
She should account for the cost of supplies. Chocolate and heavy cream is more expensive than powdered sugar and shortening.
My american buttercream cakes are 2.15/serving and chocolate ganache/european buttercream is 2.50/serving.