Pretty Vanilla Marshmallow Celebration Cake

I made this for my brother's (Jack) 17th birthday. I originally got this recipe from bbc good food website: http://www.bbcgoodfood.com/recipes/10860/easy-vanilla-cake, this gives a basic recipe to use as a base.
Then:

1. Using the 'basic vanilla buttercream' recipe from the same link above make the buttercream frosting for the cake and add pink or red food colouring until it reaches a nice shade of pink.
2. Cut the cake into three layers. It is best to use a long serrated knife for this.
3. With a palette knife, spread the buttercream between each layer to sandwich them together. 
4. Then, spread the rest of the buttercream evenly to cover the cake.
5. To make the edible sugar bow, use ready to roll icing/fondant/ gum paste. I used this website: http://www.cakejournal.com/archives/how-to-make-a-gum-paste-bow. White for the bow, then mix in some red/pink food colouring to extra paste to get a shade of pink to match the icing of the cake. Roll this out quite thin and cut out small circles (I used a pen lid) and stick onto the bow with a bit of water.
6. Position the bow onto the iced cake, letting the ends drape over the sides.
7. Using alternating white and pink marshmallows, cover the sides of the cake (I used mini marshmallows cut in half so they weren't as long). Work around the bow.
8. Then, write a message or another decoration on top. I used white writing icing to say 'Happy 17th Jack'

My brother LOVED it, delicious with a custard flavour perfect for kids and grown-ups!