Preheat your oven to 180°C (350°F).

In a large bowl, combine the crushed digestive biscuits and melted butter. Mix well until it resembles wet sand. Transfer this mixture to a 9x9 inch baking dish and press it firmly down to form the crust.

In another bowl, combine the softened cream cheese and icing sugar, mixing with a hand mixer until smooth. Add in the vanilla extract and melted chocolate, mixing until well blended. Then add in the eggs, one at a time, until just combined.

Pour the cheesecake mixture over the prepared crust, smoothing the top with a spatula.

Bake for about 30 minutes or until the centre is just set but still slightly jiggly.

Once out of the oven, let the bars cool to room temperature before covering and transferring to the fridge to set for at least 4 hours, or overnight.

Before serving, melt the chocolate you saved earlier and drizzle it over the chilled cheesecake bars.