Ingredients
250g butter room temperature
4 tbsps icing sugar
4 tbsps custard powder
11/2 cups plain flour

Icing
1 1/2 cups icing sugar
2 1/2 tbs soft butter
2 tsps vanilla extract

Method
Cream the butter, vanilla extract and icing sugar together until it is pale and fluffy.
In a seperate bowl sift the flour and custard powder together.
Continue beating the butter/icing sugar mixture and gradually add the flour/custard powder mix to it.
When combined weigh the whole mixture and divide the number by 24. Weigh each ball of dough to match that number (25g each were mine) This recipe makes 12 melting moments so you need 24 balls of dough.
Place on a tray line with wax paper, leaving space between each one (they will spread a little) and pop in the fridge for 5 minutes. This will stop them spreading in the oven.
Remove from the fridge and press each ball of dough lightly with a fork.
Bake on 150°C for 15 to 20 minutes, oven depending. They should not be brown in colour.
Remove from the oven and leave to go completely cold.
Mix the icing mix ingredients together and pipe on to the flat base of 12 cookies. Sandwhich the other 12 on top.
Serve.

Notes
I always double the recipe as they are delicious. Take care as they will crumble very easily.