To make the pastry, put the flour, cocoa powder, caster sugar, vanilla essence and butter in food processor and blend.
Take out and knead together – chill for 10 minutes
Roll out to about 3mm thick and press into a tart tin
Line with baking paper and fill with rice or pasta (blind bake)
Bake at 160°C for about 20 minutes or until the pastry is crisp
To make the filling, gently simmer all the filling ingredients together, until melted. Allow mixture to cool slightly then pour into a cooled base and set for 4 hours.