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

In a mixing bowl, combine crushed digestive biscuits with melted unsalted butter, pressing into the bottom of the springform pan.

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

Add eggs one at a time, blending well after each addition.

Stir in double cream, orange zest, orange juice, melted dark chocolate, and vanilla extract until fully combined.

Fold in chopped orange-flavored milk chocolate gently.

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

Bake for 45 minutes to 1 hour until the edges are set but the center wobbles slightly.

Turn off the oven, leaving the cheesecake inside with the door ajar for an hour to cool gradually.

Refrigerate for at least four hours or overnight before serving.

Remove from the springform pan, garnish as desired, slice, and serve.