Preheat your oven to 160°C (320°F) and grease a 9-inch springform pan with butter, then line with parchment paper.

Crush the digestive biscuits into fine crumbs and combine with melted butter. Press into the bottom of the springform pan.

Beat the softened cream cheese and caster sugar together until smooth.

Add eggs one at a time to the mixture, beating well after each addition.

Mix in the double cream, orange zest, orange juice, melted dark chocolate, and vanilla extract until smooth.

Fold in the chopped orange-flavored milk chocolate.

Pour the cheesecake batter over the prepared crust and smooth the top.

Bake for 45 minutes to 1 hour until the edges are set and center has a slight wobble.

Turn off the oven, crack the door, and let the cheesecake cool for an hour.

Refrigerate for at least 4 hours or overnight before serving.

Remove from pan, garnish if desired, and serve.