Measure and set aside the butter cubes and the cream so they are ready to go when you need them.

In a deep, medium saucepan over low to medium heat, melt the sugar. Stir it gently with a wooden spoon or heatproof spatula while it melts. It will first clump together, then gradually melt into an amber brown liquid. 

Don't turn the heat up high or let it cook for too long or the sugar will burn and the caramel will be bitter.

Once it has all melted, switch to using a whisk and add in the cubes of butter, two cubes at a time. Start whisking straightway while you do this and don't stop until all the butter has melted. It will form a thick caramel.

Once the butter has completely melted into the sugar, pour in the cream and keep whisking. Take extra care here as the cream will make the caramel bubble and rise. It may also split the caramel as the cream hits the hot sugar.

Keep on whisking and cooking it until it forms a smooth and runny deep brown caramel sauce.

Take it off the heat and stir in any extra salt if using it. If making regular caramel sauce, adding in an extra pinch of salt will enhance the flavor. For a salted caramel sauce, add in 1/2- 1 teaspoon of salt according to taste.

Leave the sauce to cool for 5 minutes, then pour it into a clean jar. It will thicken up as it cools down.

Storing

Store the caramel sauce in a sealed jar or airtight container in the refrigerator for up to a month. It will thicken up considerably and have a scoop-able firm consistency once chilled.

It can be gently rewarmed when needed to make it liquid again. Warm it in the microwave or place the jar of caramel in a bowl of hot water to warm it.

Caramel sauce can be frozen too, in an airtight container or sealed jar for up to three months.