Preheat the oven to 180C/350F/Gas 4. Grease a 9-inch springform pan and set aside.

Mix together the Oreo crumbs. and melted butter. Press the crumb mixture into the prepared pan, and bake for 8 - 10 minutes. Leave to cool completely on a wire rack.

Cover the outsides of the pan with heavy duty aluminum foil (twice, just to be sure) to prepare it for a water bath.

Turn the oven temperature down to 150C/300F/Gas 2.

Using a handheld or stand mixer fitted with the paddle attachment, beat the cream cheese, sugar and flour until smooth and combined. Beat in the eggs and egg yolk, one at a time, then mix in the yoghurt.

Divide the batter evenly between two bowls. Add the melted chocolate to one bowl, and stir until combined. Pour over the Oreo crust.

Add the dissolved coffee to the other bowl and mix until combined. Spoon over the chocolate layer, and smooth out gently.

Place the pan into a large roasting pan. Pour enough boiling hot water into the roasting pan to come 1-inch up the side of the cheesecake pan.

Bake for 1 hour or until the centre is almost set and the edges are slightly puffed. Turn the oven off and leave the cheesecake inside for 30 minutes without opening the door.

Open the door slightly and leave the cheesecake for another 30 minutes. This cooling process helps the cheesecake to cool slowly to prevent cracks.

Remove from the oven and leave for 15 minutes before removing from the water bath and foil. Chill in the fridge, uncovered, for at least 4 - 6 hours, preferably overnight.

Microwave the chocolate and butter in 20 second intervals, stirring after each one, until melted and smooth. Spread over the cheesecake.