Crust: Preheat oven to 180 C. Beat together the margarine and sugar. Add the egg and mix well.
Mix cinnamon and flours together. Gradually add to the egg mixture to form a soft dough. Press the dough into a 22 cm tart or pie dish.
Prick with a fork and bake for 15-20 minutes or until golden brown. Allow to cool.
Filling: Place milk in a pot, bring to the boil and remove from heat. Beat eggs and sugar well.
Mix cornflour with a little water to make a paste. Stir into egg mixture.
Add half the milk into egg mixture and stir well.
Pour egg mixture into the pot with the rest of the milk and stir well.
Return to a low heat and stir all the time. Allow to simmer very gently until it thickens – at least 10 minutes.
Stir vanilla in and pour into pie crust. Allow to cool and refrigerate. Sprinkle with cinnamon and serve.