Blitz your biscuits in a food processor, or bash them up to a very fine crumb in a bowl.
Add in the cocoa powder, and mix.
Add in the melted butter, and mix to a wet sand texture!
Press into the bottom and sides of a 23cm loose bottomed tart tin for best results!
For the filling
Chop your chocolate up finely, and cube your butter to as small as you can. Add to a large bowl.
Add your double cream and Baileys to a pan, and heat until just before boiling point.
Pour the mixture over the chocolate/Baileys and whisk/stir until smooth. If there are any lumps that haven't quite melted, whack the mixture in the microwave for 10 seconds at a time until melted fully!
Once melted - pour the mixture into the tart tin. Sometimes I find this easier to do in the fridge, to save me having to carry the full shell of runny liquid.
Leave the tart to set in the fridge until solid - it will take at least 3 hours!
For the Decoration
Whip together your double cream, Baileys and icing sugar until pipeable - pipe with your favourite piping tip onto the tart case.
Decorate by grating some chocolate over the top, and enjoy!