In a large bowl beat the butter until smooth and creamy.
Add in the sweetened condensed milk and powdered sugar and mix until combined.
Stir in the flour, baking powder, and salt. Mix until just combined.
Place the dough in the refrigerator for 15 minutes.
Meanwhile, preheat the oven to 325 degrees.
Take the dough out and use a small cookie scoop to scoop the dough onto the cookie sheet leaving 2 inches in between the dough balls.
Bake for 8-10 minutes. Remove from oven and let cool for 3 minutes before removing to a wire rack to cool completely.