For the cake:
Take your first cake pan and draw round it twice onto parchment paper. Cut out both circles. Measure the circumference of the pan with string, then cut a long strip of paper the length of the string and fold in half lengthwise. Grease the pan with melted butter and place one of the paper circles into the bottom. Grease, then add a second circle and grease again. Press the paper strip onto the inside edge of the pan and grease. If you're making multiple tiers, repeat with the other pans.
Preheat the oven to 350 degrees F (180 degrees C). Put the butter and sugar into a large bowl and beat together until light and fluffy. Gradually beat in the eggs, vanilla, salt, and all-purpose flour to prevent the mixture from curdling. Add the cake flour, unsweetened cocoa, and baking powder and give it a final beat to mix together. Add the food coloring and mix well. Spoon into the prepared pan and bake for the recommended time (small 30 to 40 mins; medium 65 to 75 mins; large 75 to 85 mins). The cake is ready when firm to the touch and a skewer inserted into the center comes out clean. Let cool in the pan for 5 minutes then turn out onto a cooling rack (you may need two racks side by side for the largest cake). Peel off the lining paper and let cool.
Making the buttercream:
Prepare the ingredients for the relevant number of tiers. You can make the buttercream in a single batch, so you'll need only one large bowl. Cream together the softened butter and confectioners' sugar until light and fluffy. Beat in the cream cheese and a few drops of vanilla extract to taste. Cover the surface of the buttercream with plastic wrap and chill until ready to use.
Cutting and layering the cakes
Using a long-bladed serrated knife carefully cut the smallest cake in half and sandwich back together with 3 heaped tablespoons of buttercream. Spread a teaspoon of buttercream onto the center of the smallest cake board and put the cake on top (this will stop the cake sliding off the board). Cut the remaining cakes in the same way, using 6 heaped tablespoons of buttercream to sandwich the medium cake and 8 heaped tablespoons of buttercream for the large one. Place the medium cake upside down on its cake board and the large cake on the largest cake board. Spread half the remaining buttercream in a thin layer over the top and sides of the cakes to cover. Refrigerate until set to the touch and then spread the remaining buttercream over the cakes to give a perfect finish.
Covering with fondant
Cut a piece of string for each cake to measure the combined length of the top and sides - this will be the size to which to roll your circle of fondant. Ice just one cake at a time, as fondant can dry out very quickly. Make sure your counter is clean and dry, then knead the fondant until warm and pliable. Place 2 tablespoons of confectioners' sugar in a small sifter and use to lightly dust your counter. Roll out the fondant to 1/6in (3 to 4mm) thick and keep turning so that it stays circular. Carefully slide your hands and arms under the fondant, then lift centrally over the cake and lay onto the buttercream (you could use a large rolling pin for this instead - simply hold the pin over the center of the fondant and flip the paste over it. Lift, then position and roll over the cake). Dust your hands with a little confectioners' sugar and rub them gently over the cake to make sure the fondant has stuck to the buttercream underneath. Use a sharp long-bladed knife to trim the edges, cutting downward cleanly (keep wiping the knife blade, or the paste will build up and make it difficult to get a clean cut). Repeat with the remaining cakes and fondant. Save any trimmings to make decorations, flowers, or frills - keep well wrapped in plastic wrap until ready to use, to prevent from drying out.
Stacking the cakes
To stack the cakes, you'll need the help of some dowel rods, because the sponge and frosting are too soft to support the weight of each other. Dowels can be bought from specialty cake stores; however, as every cake is different they do need to be cut to size. Only the bottom two tiers need them, so you will need eight rods in total. Hold a rod at the side of the cake and mark with a pencil where the frosting comes to. Cut the rod and three others to the same length. Push the rods into the cake about 2in (5cm) away from the sides, to form the four corners of a square in the center of the cake. They should not rise above the level of the frosting. If you have miscalculated and the dowel is too long, remove it and shave off any excess with a sharp knife. Measure, then cut and insert the rods in the same way for the medium cake. The three cakes can now be stacked directly on to each other. Once they're stacked, it's best not to move them about, so it's safest to assemble them at your venue or in the position you want them to be displayed.
Serve with Bride and Groom and lots of alcohol!