Christmas cupcakes

Name: Christmas cupcakes
Prep time: 20 min
Cook time: 25 min
Total time: 45 min
Cuisine: American
Ingredients: 280g self-raising flour; 175g golden caster sugar; 175g unsalted butter , very soft; 150g pot fat-free natural yogurt; 1 tsp vanilla extract; 3 eggs; 85g unsalted butter , softened; 200g icing sugar , sifted; natural green food colouring (for Christmas trees), sweets, sprinkles and white chocolate stars; milk and white chocolate buttons and natural colouring icing pens, available at Asda