Add whey to a medium pot and set to a medium to medium-low heat and stir every 10 minutes or so.

Keep the whey on the same heat and stir occasionally until reduced by half.

Whisk the brown sugar into the reduced whey until well combined.

Keep your pan on medium heat and reduce again by half. Whisk every few minutes to ensure the bottom does not burn. The color should continue to deepen as the mixture reduces.

After the whey and brown sugar mixture has reduced by half, add your salt and vanilla extract and mix well.

When all ingredients are well incorporated and your mixture has thickened, transfer into your pint canning jar to cool.

Your caramel sauce is now ready to be used! Enjoy this caramel sauce on delicious treats or desserts.