Caramelise the sugar in a saucepan. (Do not stir, swing the saucepan if necessary.) Not too hot!
When the colour is right, add the butter in, piece by piece.
Stir with a whisk to a homogeneous mass.
Add the salt.
Slowly add the cream and stir until a creamy mixture is formed.
The amount of cream depends on the desired consistency. If the caramel should be rather firm, 150g of cream is enough. If you want it to drizzle over the top, 200g of cream will be fine. (I used 200g of cream in the photos).
Pour into a clean jar and store in the fridge when cool.
When the Salted Caramel Sauce gets cold, it becomes even more firm.