Add the milk and sugar to a pot and place over high heat.
When it comes to a rolling boil, adjust the heat to maintain the boil while keeping it from boiling over.
Continue to boil it down, stirring occasionally.
When the amount is reduced by about 1/3 and it looks like it has thickened a bit, add the vanilla essence and immediately remove from heat.
Place the pot over cold water to cool the mixture while you mix. This will thicken it.
Transfer to a container and refrigerate.
At our house, we like to spread this on bread every morning. My sons are addicted to this as of late.
Story Behind this Recipe
My sons love condensed milk, and so I thought vanilla condensed milk would probably be delicious too.
It will thicken as it cools, so if you boil it down to a thick consistency, the condensed milk will be very firm. Remove the pot from the heat when it looks like it's still not quite ready as it'll continue to cook in residual heat.