In your saucepan, warm up the milk but don't let it boil.
In a separate bowl, whisk together the cornflour, sugar, eggs, vanilla essence, and a pinch of salt until it's well mixed.
Gradually whisk the warm milk into the egg mixture, a little at a time to avoid scrambling the eggs.
Pour this mixture back into the saucepan, and heat it gently while stirring continuously. You're looking for a thick, custard-like consistency.
Once thickened, pour the filling into your baked crust.
Dust the top with a bit of ground cinnamon
Put the tart back into the oven and bake for about 15 minutes. You want the filling to set but still have a slight wobble to it.
Let it cool, then pop it in the fridge to chill for a couple of hours before serving.
