Add all the ingredients (except for vanilla extract) to a small pot or saucepan.
Whisk togehter well until no clump is left.
Bring to a boil, then reduce heat to simmer and continue to whisk to ensure the heat is distribured evenly.
Allow ingredients to simmer for 15 - 20 minutes until the caramel becomes a dark amber color.
Turn off the heat and whisk in vanilla extract (optional).
The caramel sauce will thicken even more as it cools. Refrigerate overnight for an even thicker consistency.
Notes
** The caramel sauce will thicken even more once it has cooled down or been refrigerated, but if you prefer a thicker consistency immediately, you can incorporate the arrowroot flour in the mix (add before heating)