This is a good idea, I think, if you need sweetened condensed milk and don't have any on hand:
Sweetened Condensed Milk
1/3 cup boiling water
4 tablespoons butter
3/4 cup sugar
1/2 teaspoon pure vanilla extract
1 cup powdered milk (recommended: Carnation)
Using an electric mixer, blend together water, butter, sugar, and vanilla.
Add powdered milk and blend until thick. Store in refrigerator for up to 1 week.