Ingredients

500ml milk
2 Tbsp cornflour
3 Tbsp self-raising flour
  (or cake flour & a pinch baking powder)
pinch of salt
1 Tbsp butter
2 Tbsp white sugar
½ tsp vanilla essence

3 large eggs

250g frozen ready-rolled shortcrust
  pastry, thawed
self-raising or cake flour, for dusting

cinnamon, for dusting
2 tsp butter

Method

In a mixing bowl, dissolve the cornflour, self-raising flour & salt in a little milk.
In a saucepan, boil the remaining milk and butter. 
Slowly pour a ladle of boiling milk over the flour mixture while stirring.
Pour the mixture back into the saucepan & simmer for 5 mins.
Mix the sugar & vanilla essence in well, remove from heat, cover with a lid & leave to cool for about 30 mins.
Separate the eggs.  Beat the egg yolks and whisk them into the cooled mixture.  Beat the egg whites until stiff & fold them gently into the mixture with a fork.

On a lightly floured surface, roll out the pastry and line a greased pie dish. Trim the edges of the pastry.
Pour the filling into the dish, sprinkle with cinnamon and dab with butter.
Bake in the oven for 35-40 mins, rotating half way, until set and just browned.
Leave to cool & serve lukewarm.