Add the freshly squeezed orange juice to a saucepan and bring to a simmer over medium heat. Continue to simmer for about 10-20 minutes until the mixture has reduced to 150ml. Once reduced, transfer the liquid to a heat-resistant jar and it in a cold water bath to bring the orange reduction to room temperature.
Meanwhile, to make the crust add the cookies and vegan butter to a food processor and blitz for about 30 seconds until evenly mixed. Line the bottom and sides of a 7.5 or 8" cake tin (with removable base) with some parchment paper. Press the cookie mixture into the base of the cake tin, and smooth it out with a spatula or flat bottomed glass, making sure it is compact. Set aside in the fridge.
For the filling, melt the chocolate over a bain-marie (double boiler). Add the orange juice reduction, melted chocolate, silken tofu, vegan cream cheese, cacao powder, vanilla extract, and orange zest to a high-speed blender and blend until smooth and creamy.
Transfer the filling into the cake tin using a spatula to smooth it out. To get the swirl effect on top, place the cake tin on top of a turntable, and use your spatula to make a swirl print on the surface of the cake whilst spinning the turntable. Place in the fridge to set for 3-4 hours (or overnight if preferred).
Once set, remove the cake from the tin. You can use a blow torch to gently heat the sides of the pan to make it easier for the cake to slide out of the tin.
Garnish the cake with vegan mini chocolate eggs, chocolate shavings, orange slices, or candied oranges.
Store in an airtight container in the fridge and consume within 3-4 days. Alternatively, you can freeze any unused slices and defrost them as needed.