Begin by whisking 1 cup of milk with the cornstarch and baking soda in the stock pot. Whisk until all the lumps are gone.
Add the rest of the milk and sugar to the pot. Turn on medium high heat.
Stirring very frequently, bring the mixture up to a boil.
Reduce the heat to medium, where it should continue at a low simmer.
Let the mixture cook down until you get a thick, delicious caramel sauce. This can be time consuming and takes me about an hour and a half.
It is done when you can drag a wood spoon or rubber spatula across the bottom of the pot and the caramel stays parted for a moment before gooping back together.
Continue to stir frequently, always stirring from the bottom to prevent scorching.
Once removed from heat you can add in a dash of vanilla or sea salt for more flavor. A little rum might be tasty too!
Ladle or pour into heat safe jars (like a mason jar) and allow to cool completely.
Store in the fridge practically indefinitely.
To eat, simply warm the jar (I like to warm it in hot water myself) or just scoop out the caramel as is.