Place sugar in a 3 qt. sauce pan and heat over medium heat until the sugar dissolves completely. As it melts, stir it carefully with a silicon spatula.

The sugar will look chunky as it begins to melt.

When all of the solids have turned to liquid, turn off the heat and whisk in the butter and cream, fully incorporating the mixture. This is when you will get the sputtering and spitting - just ignore it and keep whisking.

Use the spatula to get at the chunks.

Use the whisk to smooth out the sauce.

Alternate between the whisk and the spatula. The whisk will incorporate the ingredients, the spatula can loosen thickened caramel from the whisk and sides of the pot.

You can turn the heat back on low and continue whisking, if you get some lumps.

Once it looks like caramel sauce, whisk in the vanilla and salt.

Pour into a clean canning jar and allow it to cool. Put the lid on the sauce. Store in the fridge until ready to use.