For the crust:
1. In the bowl of an electric mixer, using the paddle attachment, cream the butter and castor sugar together until pale in colour.
2. Add the egg, mix through and scrape down the sides of the bowl.
3. With the motor on low speed, gradually sift in the flours. Add the oil and mix just until a soft dough forms.
4. Form the dough into a disc, cover with plastic wrap and refrigerate for at least 30 minutes.
5. Roll the dough out on a lightly floured surface to a thickness of about 5 mm.
6. Line an enamel plate with the dough and trim the edges.
For the filling:
1. Preheat the oven to 180 °C. Grease or spray a 25- cm ovenproof dish.
2. In a saucepan set over moderate heat, slowly bring the milk to a boil.
3. Whisk the eggs and sugar together.
4. Make a smooth paste with the cake flour and water.
5. Remove the milk from the heat, then pour slowly into the egg mixture.
6. While stirring, add the flour paste until well blended.
7. Pour the filling into the prepared crust.
8. Dot with butter and sprinkle with the cardamom.
9. Bake for 40 minutes or until the custard has set.
10. Sprinkle the edges of the pastry with castor sugar to decorate (optional).
Extracted from The South African Milk Tart Collection by Mari-Louis Guy and Callie Maritz, published by NB Publishers.