Measure the sugar into a medium saucepan. If you’re using cream of tartar, mix it into the sugar.
Place the saucepan over medium heat and stir every 10–15 seconds with a wooden spoon.
After about 90 seconds, the sugar will start to melt and begin to change its color to light golden.
Keep stirring as it clumps and changes from white to light golden, then to a deeper golden brown. The darker it gets, the fewer sugar crystals you should see.
If the sugar starts to smoke or darken too quickly, remove the pan from the heat for a few seconds.
Once the sugar has fully dissolved, take it off the heat and stir for another 10–15 seconds.
Add the butter while stirring, then slowly pour in the heavy cream and continue stirring until smooth and golden.
Transfer the caramel to a glass container, or use.
