Switch the oven to 180 °C. Grease the oven pan with margarine.
Place the butter or margarine in the mixing bowl.
Stir in the icing sugar, custard powder and vanilla essence.
Add the cake flour and knead the mixture with your hands until it forms a smooth piece of dough.
Press the dough into the bottom of the oven pan, spreading it evenly with the spatula.
Prick holes in the dough with the fork.
Bake for 20 minutes. Remove from the oven, using the oven gloves and place on the wooden board.
Cut the pastry into about 20 squares with the knife and leave to cool.
Lift the biscuits out of the pan using the knife and arrange on a plate.
Makes about 20 biscuits
This is also a recipe your children can make themselves.