Place the 2 cups of heavy cream, the butter, and your sugar substitute in the pan. Stir it occasionally so it doesn’t burn but you don’t have to mix it all the time. I used a whisk.
When the mixture starts to bubble up, I reduced the heat to low and let it simmer until the 15-minute timer is up.
Notes
You will notice the mixture is thick and creamy when it’s done. It has almost reduced to about half the amount as before you started.Note: Erythritol is about 70% as sweet as sugar whereas Isomalt is about 40% sweet as sugar.