Soak the cashews in water for 12 to 24 hours. Alternatively, you can simmer the cashews for 10 minutes or soak them in boiling water for about 40 minutes.
Drain and rinse the cashews, and discard the soaking water.
Add the cashews to a blender, along with the hot water and the sugar, and blend it for 5 minutes.
Remove the blended cashews from the blender, put them in a pot, and over low heat, stir the cashews until they thicken up and start to lift from the bottom of the pot. Do not try to speed this step by using a higher flame, otherwise, it will create cups and the cashew paste can burn.
Add the cashew paste back to the blender, add the baking soda, and blend for 5 minutes more.
You can keep the condensed milk in the fridge for up to 15 days or you can freeze it for 2 up to two months.
SUGAR SUBSTITUTION: You can add erythritol instead of sugar or add a bit less sugar, however, the stated amount of sugar is important for the condensed milk's proper caramelization.