Add the butter and granulated erythritol to a medium saucepan over medium heat. Bring to a boil and then cook until it turns light brown, about 3 to 4 minutes, swirling the saucepan occasionally.

Add the cream, molasses, vanilla, cream of tartar, stevia glycerite, and salt. Bring to a boil, and then cook until the sauce is thickened slightly (it should coat the back of a wooden spoon), about 3 to 5 minutes. (Don’t overcook it, because it’ll thicken more as it cools and it will set into a thick caramel paste if refrigerated overnight.)

Serve hot.