For the cakes
Preheat the oven to 160C 325F Gas Mark 3
Place 12 cupcake cases on a baking tray.
Beat the butter and sugar until creamy
Add the rest of the ingredients, except for the jam and beat until smooth.
Divide the mixture evenly between the cupcake cases.
Place in the oven for 25-30 minutes, until they spring back when touched.
Leave to cool.
When they are cool use an apple corer to remove the centre from each cake. Fill the hole with jam then add the cake centre you removed to the top of the jam.
For the buttercream frosting.
Whisk the butter until soft and creamy.
Gradually add the icing sugar and vanilla essence and beat until smooth
Add the milk a little at a time until the mixture is soft and spreadable.
Use a piping bag to create swirls on top of the cupcakes.
Decorate as required.