Crust

1. Preheat oven to 180 Celsius.
2. Grind the wine biscuits, either in a food processor or if you don't have one (I don't) like so: put the unopened packet of biscuits inside a strong plastic ziploc bag, and then put that inside a pillowcase or tea towel. Beat thoroughly with a rolling pin - check occasionally to see if it is fully ground. Make sure to shake the bag around - often the fully-ground outside will conceal large pieces of biscuit.
3. Combine all crust ingredients, press very firmly and as evenly as possible into a pie plate and bake at 180 (160 fanforced) for 5-8 mins. This burns very easily - better underdone than overdone. Leave the crust to cool.

Custard

4. Meanwhile sprinkle 1 tablespoon gelatine on 1/4 c water and set aside.

5. Put  1c milk in a good microwave-safe pouring jug.
6. In a pot mix egg yolks, sugar and cocoa with enough of the milk to form a wet paste.
7. Gently heat the remainder of the milk (microwave is easiest and creates fewest dishes). Put the pot with the chocolate mixture onto an element on medium low and gradually add the milk, stirring constantly. Heat the custard until it thickens somewhat (all foam has gone and it coats the back of a spoon). Do not allow it to come to a boil - if it's not very thick when it begins to boil, don't worry.
8. Take the custard off the heat and beat in the gelatine and 1 teaspoon vanilla essence. Set aside to cool.

Meringuey Bit

9. When the pie crust and the custard are completely cool, beat 3 egg whites until stiff peaks form. Taste your chocolate custard at this stage - if your cocoa is very dark, you may want to add one or two tablespoons of sugar to the mixture at this stage.
10. Fold egg whites into chocolate custard.
11. Pour into biscuit-lined pie dish and refrigerate until set (at least a couple of hours). Decorate with walnuts and whipped cream.