Using a food processor, blitz all of the biscuits to a fine crumb and add the cocoa powder.
Add in the melted butter and mix until it is a wet sand texture.
Press this into the sides and base of a 23cm pie/flan/quiche tin (mine was 3cm deep).
I press into the sides first, then the base. Refrigerate for now.
Filling
In a bowl, add the icing sugar and peppermint essence
And enough water, 1 tsp at a time, until it forms a thick paste – spread across the biscuit base carefully.
Ganache
In a heatproof pan, add your double cream and heat until just before boiling point.
In a separate bowl, add the milk chocolate, dark chocolate, and unsalted butter and pour on the hot double cream. Whisk together until smooth!
If the chocolate is still slightly not melted, heat for 10 second bursts in the microwave until combined well. Alternatively, add all ingredients to a large bowl and microwave/whisk until smooth.
Pour the chocolate mixture onto the mint filling and refrigerate for an hour.
Decoration
After the hour, carefully decorate with the after eights. You want the ganache to be starting to firm, but not be completely set. This is so that they don't sink, but also soft enough that they stick.
Set again for another hour or two until set.
Add on some fresh mint leaves, and chocolate curls/sprinkles. Enjoy.
Notes
This dessert will last in the fridge for 3 days, covered.