Preheat oven to 375F.

Crumble the Digestive biscuits in food processor or plastic bag and rolling pin. You should have about 2 cups total of biscuit crumbs.

Add cinnamon and melted butter to the crumb in a bowl. Stir until the crumbs are evenly coated and look wet. The crumbs should hold together in a clump if you press them in your fist; if not, add water a tablespoon at a time until this happens.

Press into a 9 inch pie pan and press them evenly along the bottoms and sides.

Bake the crust for 8 to 10 minutes until dry and fragrant. Cool completely.

Place the cinnamon stick and cardamom in the milk and scald the milk. Do not boil milk. Remove the cinnamon stick .

Beat eggs in a bowl and add the sugar, flour, cornflour and salt, mixing well.

Add 1/4 cup of the milk to the eggs while mixing to bring the temperature of the eggs up without scrambling the eggs. Add another 1/4 cup of the milk once more. Add the egg mixture to the rest of the milk.

Return this to the stove on medium heat and whisk gently but constantly until the mixture thickens.

Add butter and vanilla extract and mix well.

Pour into cooked shell. Leave to cool for several hours until set.

Allow to cool on a shelf until it is room temperature and then transfer the tart to the fridge.

It will take a few hours for the mixture to cool, and set properly. Once cooled sprinkle with cinnamon.