Let's start cooking!
Caramel sauce: put the sugar, butter, water and salt in a saucepan. Cook on high heat, mixing with a wooden spoon for 2 to 3 minutes, or until the sauce turns golden.
Take the saucepan off the heat and carefully pour in the cream, taking care not to splash (the caramel is very hot). Mix vigorously until the sauce has a smooth consistency (put on the hob again for a few minutes if the caramel crystallises).
Leave to cool down at room temperature, then place in the fridge for 30 minutes until the caramel has slightly hardened.
Preparation of the caramel cake: preheat the oven at 180°C (350°F).
Put the chewy caramel sweets in a saucepan with the butter on medium heat, mixing with a wooden spoon until the caramel sweets have melted and the mixture is smooth and consistent. Set aside.
Beat the eggs and sugar in a large bowl. Add the melted caramel pieces and whisk. Add the flour and salt.
Pour the mixture into the mould. Bake in the oven for 25 minutes, or until the outside of the cake is baked, but the inside is still soft. Leave to cool down at room temperature for 15 minutes.
Pour the caramel sauce over the middle of the cake, break up the Belgian Chocolate Thins and sprinkle on top.