I use this recipe if we have milk that is about to go out of date. It extends the life of the milk, and can be used in tray bakes, to make milk caramel or in Vietnamese style coffee.
A note on the ingredients: Use full-fat milk or the ratio will be off. The ratio is 1g sugar for every 3mL milk, so do your own calculation for the amount of milk you have. I have made this using white sugar, brown sugar, caster sugar and even on one occasion, local honey. It is a versatile recipe.
165g granulated sugar
Place milk into the pot with the sugar and heat to dissolve the sugar. Turn heat down and cook over medium heat for 30 minutes until the milk has reduced and thickened. It will thicken further as it cools. Try not to stir as it cooks as this will cause the sugar to crystalise.
Cool at room temperature and then store in the fridge until needed.