Chocolate caramel tart

Name: Chocolate caramel tart
Prep time: 5 h
Cook time: 30 min
Total time: 5 h 30 min
Cuisine: European
Ingredients: 1/3 cup hazelnuts, toasted, chopped; Nonstick cooking spray; 3/4 cup plain flour; 1/3 cup cocoa; 1/2 tsp fine sea salt; 85g unsalted butter, softened; 1/2 cup caster sugar; 1 cup caster sugar; 2 tbsp water; 1 tbsp golden syrup; 2 tbsp cream, at room temperature; 110g unsalted butter; 1 tsp flaked pink salt, or sea salt; 1/2 cup thickened cream; 80g good quality dark chocolate (70% cacao), chopped