Presently, I am making the mousse using a recipe in Nancy Silverton's book "Desserts", ie. melting chocolate, adding it to an egg yolk mixture that had a sugar syrup beaten into it first, then folding in the whipped cream and refrigerating the mixture. I would like to be able to use the mousse in either genoise or butter cakes, depending on the bride's preference. I want the mousse to be firm enough to slice cleanly when the cake is cut (after it has been sitting out at the reception site for approximately 3 to 4 hours indoors, with air conditioning). The cake would be covered in fondant. Previously, when I've made white chocolate mousse, I've used it as a dessert. Last week I attempted to fill a cake with it and could see immediately that it was going to "squish" out when sliced, so I substituted white chocolate mousseline buttercream (recipe from Rose Levy Berenbaum's "The Cake Bible". Do you feel that a genoise cake can successfully be covered in fondant? I've always thought that it would be too heavy on a light cake and therefore was reluctant to use it.
