Base:
Melt the butter and cocoa together in a pot over a low heat. Blast the biscuits in a food processor until they're fine crumbs. Pour the crumbs into the pot and mix it all together thoroughly.

Line a cake tin with cling film so there's lots of overhang (to help pull it out afterwards).

Press the biscuit mixture into the bottom of the cake tin

Top:

Slowly warm the lemon juice and sprinkle gelatine over the top. Stir until it melts and then take off heat and set aside to cool.

Into a large mixing bowl put the room temperature cream cheese, caster sugar and lemon juice and mash it or blend in the food processor until smooth.

In another bowl whisk the evaporated milk until light and fluffy. Tip into the cream cheese mixture.

Whip the cream until thick and fold that into the mixture until it's all mixed well.

Pour onto the crumb base.

Cover and chill in the fridge overnight. Then to really set it properly chuck it in the freezer. Serve on it's own or with icecream.