• Preheat the oven to 180 degrees Celsius/ 350 degrees Fahrenheit.
• Line a 20 cm/8-inch springform with a double layer of strong aluminum foil on the outside.

Crust:

• Melt the butter.
• Place the digestives and the butter in a food processor and process until you get wet crumbs.
• Press the crumbs into the bottom of the prepared pan and place it in the fridge while you make the filling.

Filling:

• Beat the cream cheese until smooth and creamy.
• Add the sugar and incorporate.
• Add the eggs and the egg yolks one at a time, whisking well after each one. Add the sour cream and the lime juice. Beat well.

Melt the chocolate:

• Place the finely chopped chocolate in a small metal bowl that fits on top of a pan.
• Pour water in the pan, place the bowl with the chocolate on top but make sure that the water doesn't touch the bowl.
• Heat the water gently, but do not let it come to a boil. Melt the chocolate, stirring often.
• Pour the melted chocolate into the cream cheese mixture and fold it in gently until everything is smooth again.

Bake:

• Place the prepared springform into a roasting tin. Boil water in a kettle and pour the water into the roasting tin to come 2 – 2 ½ cm/ ¾ – 1 inch up the sides of the cake pan.
• Bake for about 1 hour until the cake is lightly browned around the edges and the center is just set on top, but still a bit wobbly underneath.
• Remove the aluminum foil and let cool on a wire rack. Refrigerate.
• Unmold and glaze before serving.

Chocolate glaze:

• Place the cheesecake on a serving platter before glazing it.
• Place the finely chopped chocolate, heavy cream, and golden syrup in a small pan.
• Heat gently while stirring all the time but don't let it come to a boil.
• When the chocolate is almost melted remove from the heat and continue stirring until the mixture is smooth.
• Let cool for a few minutes, then pour some of the glaze over the cake.
• Serve the remaining glaze on the side.