Preheat the oven to 180C/gas mark 4. Lightly grease and flour each mould of the mini Easter egg silicon moulds.
Sift the flour with the baking powder and set aside. Cream the butter and sugar until light and fluffy. Add the vanilla and lemon zest then the eggs one at a time, beating well between each addition.
Add half the flour and then half the milk and mix until fully combined. Repeat with the remaining flour and milk.
Divide the mixture into the prepared cake moulds and bake for 18 minutes or until a cocktail stick inserted into the centre of each cake comes out clean. Leave to cool for 20 minutess then turn out onto a wire rack to cool completely.
To decorate, melt each colour of candy melts in microwave safe bowls. Melt each bowl for one minute, stir, then 30 seconds, stir, then repeat once. Use a teaspoon of vegetable oil in each bowl to smooth out the candy.
Dip the raised side of each cake into the candy, you can use a fork to do this. Use four cakes per colour.
Place on a sheet of baking paper to dry, about one minute.
Pour each colour into individual disposable piping bags, cut the end off. Pipe Easter Egg designs onto each cake. Leave to dry.