Add the oats into a small bowl, fill with water, cover and allow it to rest for at least 8 hours or overnight in the fridge. Alternatively, you can boil the water then pour it into the oats, and wait until the water has cooled enough so you can handle it.
After the resting time, take a medium size pan, lined with a cheesecloth, then pour the rested oats along with its water into the cheesecloth, squeeze the cheesecloth as much as you can, and discard the oats - but don't throw them away, you can use it for smoothies, cakes, bread, fritters, etc.
Take the pan with the oat milk to the stove, over medium heat, then add the sugar, salt, and optional vanilla essence.
Stir until it thickens up considerably, transfer to a clean and sterilized jar and enjoy it!