Kirsty Allsopp’s chocolate heaven cupcakes

# Preheat the oven to 180°C, (160°C for fan ovens), Gas Mark 4. # Place the flour, cocoa powder, condensed milk, egg, vanilla extract, buttery spread and baking powder in a bowl and beat with an electric hand mixer for 2-3 minutes until pale and fluffy. # Spoon into the cases and bake for approximately 15-18 minutes until springy to the touch and golden brown. Cool slightly then transfer to a cooling rack to cool completely. # Beat the icing sugar, cocoa powder, buttery spread and vanilla with enough condensed milk to bring the mixture to a soft consistency. Spread or pipe onto the cakes. Decorate with the Nestlé Smarties.