To prepare the caramel, place the sugar in a small saucepan and heat over medium low heat (3 or 4) for about 15-20 min. As the sugar heats up, it will initially start to clump together, this is normal!
Continue to let the sugar melt down and caramelize, stirring regularly or swirling the pan regularly until all the sugar has completely melted and has turned a lovely amber color. This may take up to 20 minutes. If using a thermometer, it should read about 350, but is not necessary to use.
Remove from the heat and add the butter. Be careful, as this will create steam and will bubble a lot. The butter will initially stay separate from the sugar, but just whisk them together until the butter has become homogeneous with the caramel.
Once combined, then add in the coconut milk and whisk until once again it has become fully incorporated and homogeneous.
If it is being a little stubborn and not coming together well, you can place the pan back on low heat and whisk until it comes together.
Allow to cool, then keep in an airtight container and place in the fridge. The sauce will keep for about a week. Enjoy!