Cream the butter and sugar together in a medium bowl. Add the eggs one at a time making sure to mix thouroughly. Mix in the sour cream, vanilla and milk.
While mixing on low speed add the wet ingredients to teh dry and mix until just combined.
Scoop the batter into cupcake papers filling 2/3 the way up.
Bake at for about 15-20 min or until golden.
Let cool.
For the Vanilla Buttercream
Beat the butter until light and fluffy.
Add the confectioners' sugar.
Transfer to a piping bag.
For the Candies:
Roll out peppermint leaf candies. Cut into heart shapes. Pinch the edges and join together. Arrange into a clover. Add a stem and a swirl on buttercream. Sprinkle sanding sugar.