Preheat oven to 180deg fan (200deg non fan).
Put 12 cupcakes cases into your tin ready.
Cream your room temperature butter with your sugar until its pale, light and fluffy.
Beat in the eggs, one at a time, mixing really well after each egg. Don't worry if it curdles slightly, it will come good.
Mix in your flour, if you are using a mixer you should do this by hand as it helps to keep the cakes moist.
Spoon equal amounts of mixture into your cupcake cases. I use an ice cream scoop as this gives the perfect amount and ensures some uniformity.
Bake for 15 minutes approx. You may need to adjust this depending on your oven. The cakes should be golden and slightly bouncy to the touch.
Meanwhile make your icing.
To make your icing beat your butter until its, pale, light and fluffy.
Beat in your sieved icing sugar.
Take your cupcakes out of the oven, when they are cooled pipe your Christmas trees.
Sprinkle over Christmas themed sprinkles.