In a large measuring jug, combine the brown sugar, butter and cream.

Microwave the mixture for 1 minute, stir then microwave another 30 seconds more. In total cook for 1.30-2 minutes. Just note it will bubble up as it cooks so keep an eye on it. Once it's golden caramel in color it will be done.

After you take it out of the microwave, add in the vanilla and salt and whisk it until it's nice and smooth and a uniform color. You want to do this immediately so it all comes together well.

At this point, you can taste it and decide if you want to add more salt or vanilla!

When you take it out of the fridge, you should heat it in the microwave for 30 seconds at a time and stir after every cycle. Keep that up until it's nice and fluid again. This caramel sauce should be good for a couple weeks refrigerated.