Place the sugar and egg whites in a heatproof bowl over a saucepan of simmering water.
Whisk for 1-2 minutes until the sugar is dissolved Remove the bowl from the heat and beat the mixture with and electric mixer until cool.
Continue beating and add the butter, a few cubes at a time (the mixture will look curdled at first).
Beat for a further 10 minutes until the mixture is light and creamy. Use a metal spoon to mix in the vanilla.
Keep in a cool place at room temperature until required.
Using a metal spatula, cover cake in butter cream.
Gently place heart-shaped cookie cutter on the cake and use a teaspoon to fill in the shape with hundreds and thousands.
Remove cookie cutter and repeat until your cake has as many hearts as your 'heart' desires.
Using your fairy fingers, lightly scatter extra hundreds and thousands around the cake.
To get the sprinkles on the sides of the cake, take a few in your fingers and throw them at the cake. They will stick but this is a messy job and you can expect the sprinkles to not only land on the cake but scatter across every corner of your kitchen. But that's half the fun!
Recipe by Hotly Spiced at http://hotlyspiced.com/a-cake-of-joy/