Preheat oven to 180C. Grease oven trays.
Beat butter, brown sugar, egg and vanilla essence in a small bowl with electric mixer until smooth. Transfer to a large bowl and stir in flour, baking powder and coconut in two batches.
Roll rounded teaspoons of mixture into oval shapes. Place about 2.5cm apart on the trays. Flatten slightly. Bake biscuits for approximately 12-15 minutes or until browned. Allow to cool.
TO MAKE CREAM FILLING: Beat butter, vanilla essence and sifted icing sugar in a small bowl with electric mixer until light and fluffy. Add milk and beat for a further minute.
Sandwich biscuits with jam and cream filling.