Pre-heat oven to 160 degrees celsius /320 degrees fahrenheit (fan-forced). Place a baking tray filled with water on the lowest shelf (this will remain in the oven as the cheesecake bakes).
Grease and line (with baking paper) a round springform cake tin (19-20cm diameter).
Base
Crush or process biscuits to achieve a fine crumb consistency.
Add melted butter to crushed biscuits and press into the bottom of the cake tin.
Cheesecake
Beat cream cheese and sugar together on high in a stand mixer for 5 minutes (10 minutes if using a handheld electric mixer).
Combine the Baileys, eggs and vanilla extract and beat lightly with a fork. Add this slowly to the cream cheese mixture and then beat on medium in a stand mixer for another 5 minutes (10 minutes if using a handheld electric mixer).
Add the grated chocolate and stir through to combine.
Pour cheesecake mixture on top of biscuit base and place into oven.
Bake for 60 minutes or until cheesecake is only slightly wobbly in the centre and a skewer inserted into the middle of the cheesecake comes out clean.
Allow to cool completely before adding the topping.
Topping
Beat sour cream and sugar for a few minutes or until thickened.
Spread evenly over top of cooled cheesecake.
Sprinkle grated chocolate over top of cheesecake.
Place into the fridge to chill before removing from the cake tin and serving.
Notes
Storing: Your cheesecake should keep a few days, covered, in the fridge.Freezing: Wrap well and store in the freezer for up to 3 months.Nutrition: The nutrition information is an automatically generated estimate and is not guaranteed to be accurate.Tips:
Make sure the cream cheese and eggs are at room temperature before baking for best results.
Before baking, place a baking tray filled with water on the lowest shelf. This will remain in the oven as the cheesecake bakes to create a moist environment and an even temperature, which assists in the cheesecake baking properly and reduces the chances of cracking. (Don't panic if the cheesecake does crack a little as it bakes as the topping will cover it all up anyway.)
The base layer will seem quite buttery – that's normal for this recipe and helps create a sensational fudgey chocolate base.
Note that the cheesecake will firm up as it cools. This is why it should still be a little wobbly looking in the centre when you take it from the oven (unlike a cake, which should be firm to touch).