• To make the crust, combine all the ingredients in a bowl and mix until evenly moistened. Press the crumb mixture into a 9-inch springform pan using the smooth bottom of a glass. Refrigerate the crust while you are making the filling. For easier removal, line the springform pan with cut-up parchment paper before adding the crumbs.
  

For the Cheesecake

• In a heat-proof bowl over barely simmering water, melt the chocolate and butter. Stir occasionally until smooth. Let it cool for a couple of minutes afterward.
  
• While the butter and chocolate are slowly melting, prepare the other ingredients. In a separate bowl or in the bowl of a stand mixer, mix together the softened cream cheese, heavy cream and sugar until it has a smooth consistency, roughly 3-4 minutes. Pour in the vanilla extract. Mix just until it’s fully blended in.
  
• Stir the cooled chocolate mixture into the cream mixture until smooth. Fold in the blueberries, if using (optional).
  
• Pour the mixture onto the prepared tin. Refrigerate until fully set. This can be made 2 days ahead. Before serving, drizzle some lemon blueberry sauce.
  

For the Lemon Blueberry Topping

• To make the lemon blueberry sauce, add all the ingredients in a small saucepan and simmer over medium heat for 5 minutes or until the fruit begins to break down slightly and the sauce has thickened to your liking. Leave to cool before spreading on cheesecake. Enjoy!