Preheat oven to 325 degrees Fahrenheit. Combine crushed graham crackers, sugar, brown sugar, and butter. Mix well. Pour into a springform pan and press down until set.

In a large bowl, stir in cream cheese and mix until creamy. Add sugar, sour cream, vanilla extract, and salt. Mix well. Add in eggs and beat until incorporated into the mixture. Pour cheesecake mixture into the springform pan, on top of the graham cracker crust.

Bake for 75 minutes. Allow to cool for 10 minutes, and then gently loosen crust from pan with a spatula or knife. Cool for another one to two hours before serving. *Remove springform pan prior to serving.

Mix water and sugar in a saucepan on medium heat. When sugar dissolves, add chestnuts, lemon juice, cinnamon, cardamom, and nutmeg. Stir until smooth. Add in chocolate bar and allow to melt. Use a spatula to smooth out lumps.

Pour over prepared cheesecake and drizzle with chocolate syrup.