Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper.
In a mixing bowl, combine softened butter and condensed milk. Mix well until smooth and creamy.
Add ¾ cup cornstarch and knead the dough until soft, if the dough is too sticky add 1 tablespoon of cornstarch first then mix until smooth. if the dough is still sticky add the remaining tablespoon of cornstarch.
Roll a tablespoon of dough into a ball and place it on the prepared cookie sheet 1 inch apart. Press down with a fork.
Bake for 13-15 minutes or until edges turn golden in color. Dust with some powdered sugar.
Let the cookies cool completely in the cookies sheet then transfer onto a wire rack.