Prepare the Pastillas de Leche soft dough:
- In a large nonstick saucepan or skillet, combine the milk and white granulated sugar. Over low to medium heat, stir continuously until the sugar is completely dissolved.
- Once the sugar is dissolved, add the unsalted butter to the mixture. Continue stirring constantly to prevent the mixture from sticking to the pan. If you want to add an ube flavor (optional), you can stir in the ube halaya/purple yam jam at this stage. Mix well.
- Cook the mixture over medium heat, stirring continuously until it thickens. This can take about 20-30 minutes. You’ll know it’s ready when the mixture becomes very thick and starts to pull away from the sides of the pan. If you want to add a hint of vanilla flavor (optional), you can stir in the vanilla extract at this stage. Mix well.
Form the Pastillas de Leche:
- Remove the mixture from heat and let it cool for 15-20 minutes until you can handle it comfortably.
- Grease your hands with a bit of butter or cooking oil to prevent sticking.
- Scoop a small amount of the mixture (about 1 tsp) and roll it between your palms to form a cylinder or ball shape.
- Roll the pastillas in white sugar to coat it evenly.
- Place the finished pastillas on a tray lined with wax paper or parchment paper. Let them cool completely.
- Once the pastillas are completely cool, you can store them in an airtight container, separating the layers with wax paper to prevent sticking.
- Enjoy your homemade Pastillas de Leche!