Add the coconut milk, apple cider, brown sugar, vanilla extract, and apple pie spice to a small pot over medium-high heat.
Whisk all of the ingredients together until well combined and bring the sauce to a boil. Lower the heat to a simmer and allow the caramel to continue simmering for 20 to 25 minutes, whisking frequently.
Once the caramel has thickened and coats the back of a spoon, remove the pot from the heat. Add in the flaky sea salt and stir until well combined.
Allow the caramel sauce to cool for 10 minutes before using. Serve it warm or allow it to come to a complete cool before transferring to a storage container and storing in the fridge.