Preheat the oven to 350 degrees Fahrenheit. Whip the butter and sugar to a smooth, creamy consistency. Add the eggs one by one into the creamy mixture.
Mix the flour and baking powder in a separate bowl. Pour the flour and 1/2 cup milk into the above mixture and fold in bit by bit until you achieve a smooth consistency.
Add any flavors or dried fruits to the cake mixture and stir. Pour in the white wine to preserve the cake.
Apply butter all around a rectangular baking pan and sprinkle with flour. Overturn the baking pan to remove excess flour. Pour the cake mixture into the baking pan and put it in the preheated oven. Close the oven door slowly to avoid entry of air.
Allow the cake to bake for approximately 35 minutes. Perform the toothpick test to check for readiness by inserting a toothpick and pulling it out after three seconds. If it comes out clean, without any traces of unbaked dough, the cake is ready. If not, leave it in the oven for five additional minutes.
Remove the cake from the oven when ready and allow it to cool for at least 12 hours. Mix the confectioners' sugar with 1/2 cup milk and a food coloring of your choice. Begin decorating by applying the first layer of the confectioners' sugar mixture. Allow each layer to dry before applying subsequent layers.
Allow the frosting to dry for 24 hours. Pour the confectioners' mixture into a piping bag and write your names, a picture of wedding bells or a special wedding message on the cake.