Fill a large cooking pan with water, melt the chocolate using a bain marie by placing the small cooking pan containing the chocolate into the larger one. Blend a piece of butter and stir to help the chocolate melt.
Once melted, add Bonny Sweetened Condensed Milk into the cream and combine well to make the mixture. Then add the bitter cocoa and coffee and stir to melt it completely (making sure there are no lumps in it!). Pour into a bowl and leave in the fridge for chilling.