Melt the butter in a pan and add the crushed digestive biscuits. I put mine in a sealed bag and had fun bashing them with a rolling pin. Mix well until the biscuits have absorbed all the butter.
Remove from the heat and press into the bottom of a springform tin. Place in the fridge and allow to set for an hour.
Meanwhile, prepare the filling. Lightly whip the cream cheese then beat in the Baileys and icing sugar. Fold in the whipped cream and grated chocolate. When smooth, spoon evenly onto the biscuit base. I rushed this step a bit, make sure you really pack the biscuit in tightly because my base fell apart a little when I cut in to it.
Refrigerate and allow to set for a couple of hours. Once set, remove and dust with cocoa powder before serving. This cake definitely tasted better the next day and well chilled so be patient.