125 gms butter softened
3/4 cup (115gms) plain flour
1/4 cup (45gms) icing sugar mixture
1/3 cup (50gms) custard powder
60gms butter, softened, extra
2/3 cup (110gms) icing sugar mixture, extra
1 tsp vanilla paste
Preheat oven to 160 degrees C. Line 2 baking trays with baking paper. Cream butter until pale and creamy in a food processor. Add the flour, icing sugar and custard powder and pulse briefly to combine.
Using your hands, roll teaspoonsful of the dough mixture into balls. Place the balls approximately 3cm apart on lined trays. Use a fork dusted in icing sugar and gently flatten. Bake in preheated oven, swapping trays halfway through cooking, for 15 minutes or until just cooked through. Remove from oven and set aside for 30 minutes to cool.
Beat the extra butter and icing sugar in a bowl with an electric mixer until light and fluffy. Add vanilla paste and beat until combined. Spread the butter mixture over the flat side of half the biscuits and sandwich together with remaining biscuits.