Place the butter in a medium sized sauce pan over low heat, once melted whisk in the sweetener and cook for 3-4 minutes until nicely browned.
Pour in the heavy cream and salt and bring to a boil, then simmer for 8-10 minutes until mixture starts to thicken. Once the mixture coats the back of a spoon and is reduced by half, it's done.
Remove from the heat and stir in the caramel extract.
Taste and adjust sweetener if needed. Use immediately and/or store in a glass mason jar in the fridge. Reheat in the microwave for 30 seconds.