Measure the three quarts of goat milk and pour all but one cup into a stainless steel pan.
Add the three cups of sugar to the pan and stir.
Add the cornstarch and baking soda to the cup of milk you set aside.
Mix until the cornstarch and baking soda are dissolved.
Pour this mixture into the pan with the milk and sugar.
Add the vanilla extract.
Bring the mixture to a boil – stirring constantly. This mixture will stick to the bottom of the pan and start to burn fairly quickly so paying close attention and constantly stirring it is important.
Cook the mixture until it is thick and creamy. It should look like caramel but still be pourable.
When the Cajeta is finished cooking to your liking, pour it into sterilized canning jars making sure to leave 1/2 inch headspace at the top of the jars.
Place the sterilized lids and bands on the jars, tighting the bands until they are finger tip tight.
Place the sealed jars into a hot water bath canner filled with boiling water.
Put the lid on the canner and listen for the sound of it to start boiling again.
Set your timer for twenty minutes.
Remove the jars at the end of this time and allow them to cool.