To make the biscuits, put the butter, powdered sugar and vanilla extract in a bowl. Using an electric mixer beat this on high speed till it becomes pale and fluffy (for about 3 minutes). Scrape the sides of the bowl down a couple of times in between.

Sift the flour and custard powder onto this butter-sugar mixture and beat on low speed till everything is just combined to form a soft dough.

Since the dough is not very easy to handle at this stage, refrigerate it for about 30 to 45 minutes till it can be easily shaped.

Then take out the dough. Lightly coat your palms with flour and pinch off equal little bits (about 25 to 30 in all) of dough and roll them into smooth balls.

Place them on parchment paper lined sheets or ungreased cookie sheets. Dip the tines of a fork in flour and lightly press down on each ball of dough, flattening it to about 1 cm high. The tines will leave a decorative mark on the biscuits.

If your balls of dough have been rolled smoothly without any cracks, they will be smooth when pressed down.

Place the sheets in the refrigerator for about 10 to 15 minutes (the time it takes for your oven to pre-heat).

Bake the biscuits at 170C for about 15 minutes or till they start looking a light golden colour. Do not be tempted to over bake them, as the biscuits will lose their melt-in-the-mouth texture.

Let them cool on the sheets for a while and cool them completely. Beat all the ingredients for the butter cream till light and smooth. Sandwich the biscuits with this buttercream.