Cake Preparation: Preheat oven to 350 degrees F. Spray each cake pan with non-stick cooking spray, line with parchment paper and spray again. Follow directions on cake mix boxes to create 3 cakes of each size, but substitute grape juice for water in cake recipes. Bake each cake as per directions on box or until toothpick inserted into center of cake comes out clean. Cool cakes in pans on cooling racks and cool completely. After removing cakes from pans and parchment paper, cut each cake in half horizontally and level off tops of each section by slicing thin layer off top.
Filling and Frosting Preparations: In a large bowl, combine frosting with a few drops of Champagne extract, stirring well. For each size cake, place bottom layer atop cardboard round of matching diameter. Pipe a ring of lemon frosting around top edges of bottom layer. Fill in center with raspberry jam. Stack next layer of cake atop this and repeat ring of frosting. Fill in center with lemon curd. Stack top layer of cake atop this with smooth edges facing upward. Spread icing over entirety of cake. Repeat this process to create a 14-inch cake, a 10-inch cake, and a 6-inch cake, which will make up finished wedding cake. Stack layered cakes atop one another from largest to smallest.
To Assemble: Without removing the cardboard rounds from underneath the cakes, place the 14 inch cake onto serving platter. Cut dowel rods into 5 sections the height of the 14 inch cake, and 5 sections the height of the 10 inch cake. Carefully insert 4 dowel rods around the middle perimeter of the 14-inch cake and 1 in the middle. Stack the 10-inch cake atop the 14-inch cake. Repeat dowel insertion process for the10-inch cake. Stack the 6-inch cake atop the 10-inch cake. Cover up cardboard by piping icing around perimeter base of each cake. Dust mini green grapes liberally with powdered sugar and adorn cakes with them. Further adorn cake with white ribbon. Find mate, wed, serve.
*Champagne extract is available at most specialty baking and cake decorating stores. .