Substituting fresh milk straight from the carton or jug will not give you a satisfactory cheesecake. Neither will evaporated milk from a can. Sweetened condensed milk has had some of its water removed and sugar added to it. To get the same results from fresh milk, sugar and sometimes butter are heated together with the milk in a saucepan until the mixture thickens.

Combine 6 cups of whole, reduced-fat or skim milk with 2 1/4 cups sugar in a heavy saucepan. Bring the mixture to a boil and then reduce the heat to a simmer. Cook the mixture until it is reduced to about 4 cups. This step takes about 50 minutes. Remove the saucepan from the heat and allow the milk and sugar mixture to cool. Pour the homemade sweetened condensed milk into a container and store it in the refrigerator for up to a week. This recipe makes approximately 32 ounces of sweetened condensed milk.

Nonfat dry milk can also be used if you are running low on fresh milk. Put 1 cup of dry milk powder in a blender. Add 1/3 cup boiling water, 2/3 cup granulated sugar and 3 tablespoons butter to the blender. Blend the mixture until it is thick and smooth. Remove the sweetened condensed milk from the blender and store it in an airtight container in the refrigerator. This recipe is roughly equivalent to a 14-ounce can of condensed milk.

Add a few drops of vanilla extract to the milk mixture when it is finished cooking on the stove or whirling in the blender. Pre-mixing the milk powder with a bit of cold water before adding the hot water and other ingredients will eliminate possible clumping. Some recipes call for melting the butter before adding it to the other ingredients.