Pour the coconut milk in a pot. Bring to a boil over a medium-high heat.Once it starts simmering, turn the heat down to low. Reduce the coconut milk to about half of the volume. This will take 40-50 minutes.Once reduced, take off the heat and add Erythritol. Although you can add the sweetener in the first step, it's better to add it after you reduce it in case you prefer different level of sweetness. Reducing the coconut milk by itself will make it sweeter and you can add as much sweetener as you like. If you want to achieve a more caramel-like taste, use Sukrin Gold instead of regular Erythritol.Pour in jars and let it cool down.Seal and refrigerate for up to a week. Alternatively, pour in an ice-cube tray and freeze for up to 3 months. The milk will be runny at first but will thicken as it chills. To make it runny, simply heat it up. Here is a batch that I made with some thickener (glucomannan powder). This may be useful for making deserts but was too thick to be used as regular condensed milk.