I followed this recipe to make condensed milk but it never thickens.
2 cups milk 1/2 cup sugar 25 gr butter
I tried it once following the recipe to a T, and when it didn't thicken not even a little bit after 30 minutes, I decided to halve the recipe and use a big frying pan so that it would thicken faster. It didn't thicken, again. It never thickens and the consistency is exactly like the milk itself.
I mix sugar with milk, then on medium heat constantly stir. After about 20-25 minutes, half of the milk was evaporated but the thing didn't thicken! What am I doing wrong?