1.Grease 2 x 12-hole muffin pans (each hole having ½ cup/80ml capacity). Using both packets, prepare cake mix according to directions; divide mixture evenly among holes in muffin pans. Bake in moderate oven about 15 minutes. Stand in pans 5 minutes; turn onto wire rack to cool.
2.Beat the butter in a small bowl with an electric beater until the butter is as white as possible. (This will result in a whiter buttercream which will give you better results if colouring it). Gradually beat in half of the sifted icing sugar, then the milk, then the remaining sifted icing sugar.Beat until the butter cream is smooth and spreadable. Keep scraping down the side of the bowl during beating.
3.Divide butter cream among seven small bowls. Tint butter cream red, pink, green, yellow, orange, blue and purple.
4.Insert a fork into the base of each cake to act as a handle. Spread tops and sides of cakes with butter cream. Arrange balloons on board.
5.Using a skewer, tuck ends of thin ribbon under some of the balloons. Bring other ends of all the ribbons together to tie with thick ribbon. Using decorating gel, pipe a letter on each balloon to spell out the appropriate message, if desired.
a carnival of cakes to delight your guests you could also personalise each cake with the name of the birthday child Tint each portion of butter cream with each of the colourings. Using a fork as a handle, spread top and side of each cake with a different coloured butter cream. Arrange balloon cakes into a bunch, tuck ends of thin ribbon under some balloons.