Use dulce de leche instead of condensed milk.
Add any sort of texture component (pinipig, shredded coconut, crushed nuts, etc.) either in the milk mixture, or as coating. Add fruit purée to the mixture for fruit-flavored pastillas de leche.
Add an appropriate cooked vegetable purée to the mixture (eg, squash/pumpkin, taro, purple yam, etc.).
Add any nut butter.
Mix together condensed milk and powdered milk until the consistency of dough.
Scoop out about a tablespoon’s worth of “dough” and roll into a log.
Roll log in granulated sugar until coated. Repeat until all the milk mixture is done.
Wrap each log in paper or cellophane.