Unsweetened condensed milk is the same as evaporated milk found in grocery stores. The milk is sold in cans with 60 percent of the water removed from the milk, making it thicker and creamier to begin with. Sweetening the milk will make it even thicker. Once you have sweetened condensed milk, you can use certain acidic ingredients to thicken it further, even creating gelatin-like setting for pies without the need for gelatin.
Pour 2 cups of unsweetened condensed milk into a saucepan.
Add 8/10 of a cup sugar to the saucepan.
Bring the mixture to a boil, stirring for 20 minutes on high heat. The milk will thicken.
Allow to cool and store in an airtight container .
Mix 1 part lemon juice to every 8 parts of sweetened condensed milk. So for every cup of milk, add 1/8 cup of lemon juice. Stir in well and store in the refrigerator for two hours to set, which is where the milk becomes gelatinous.
Lime juice can be substituted for lemon.