Do not stir the sugar and butter as it dissolves. If you need to, swirl the mixture gently to combine the ingredients, but not much. You want the caramelization to start from the bottom and let it work its way up.
If you find that you end up burning some of the sugar before the rest of it is melted, the next time you attempt your caramel sauce, add a half cup of water to the sugar at the beginning of the process. This is called a “wet” caramel sauce. (See below. ) The wet caramel sauce recipe will help the sugar to cook more evenly, although it will take longer to cook—the water will need to evaporate before the sugar will begin to caramelize.
If sugar crystals start forming on the sides of the pan, use a brush to wipe them back down into the mixture.
This is the time to really guard against burning. You don’t want to leave the sauce unattended at this point. If you’re worried about the sauce burning, you can turn the heat down to low. It’s better to take a little longer cooking than to hurry the process and burn the caramel. Keep resisting the urge to stir. Swirl if you need to, but don’t stir yet!
Mix in the cream in small batches and stir vigorously. The mixture will foam up and grow in volume. As you mix in the rest of the cream, the sauce will turn a darker color. The sauce will keep on bubbling as the cream gets incorporated into the sugar and butter.
Store in the refrigerator for up to 2 weeks. Warm it up before serving.
When the mixture comes to a boil, turn the heat down to medium-low, and stop stirring completely to prevent crystallization. Allow mixture to boil undisturbed until it turns a deep amber. It should look like the color of dark beer. You can also use a thermometer to determine when it is time to stop cooking. The mixture should reach 350 to 375 °F (177 to 191 °C).
Scrape the thick parts that settle on the bottom. If lumps develop, put the pan on the heat again, and stir until the lumps dissolve.
Strain into a heat-resistant bowl or jar and wait until caramel sauce is cool enough to serve.
If you need to store, this sauce will keep for up to 7 days if covered and refrigerated.
