Preheat the oven to 180°C (160°C, gas mark 4) and line a 12 hole cupcake tin with cupcake cases.
Cream together the butter and sugar until pale and fluffy, then add the beaten eggs one by one and the vanilla extract, mixing well between each one to ensure the mixture does not curdle.
Sift in the flour, cocoa and baking powder and carefully fold in until just incorporated, do not over mix. Then add the red colour and carefully mix until distributed evenly through the batter.
Spoon into the cupcake cases until they are 2/3 full then place in the oven for 25 minutes or until a skewer comes out clean and the cakes are springy to the touch.
Remove from the oven, leave to cool then transfer to a cooling wire to cool completely.
Whilst the cakes are cooling you can make the sugar paste hearts. Knead the red and white sugar paste icings and to make pink add a small amount of red to some of the white and knead until the colour is uniform, repeat until you have the desired shade of pink. Roll the icings out on a surface dusted with icing sugar until they are about 2-3mm thick, then cut out different sized hearts using heart shaped cutters. Put to one side on some baking parchment to set whilst you make the rest.
To make the buttercream, place the butter and icing sugar in a large bowl with the vanilla extract and start to beat together slowly to start with then increase the speed and beat until the buttercream is light and fluffy. You can add a few drops of food colour here if you wish.
Pipe or smooth buttercream onto the top of each cake using a piping bag or palette knife, then place the rolo on top. Add sweets as extra decorations if desired.
Cupcake are ready for velentine celebration.