Step 1: Preheat your oven to 350°F (175°C). Line a baking sheet with parchment paper or a silicone baking mat.
Step 2: In a large mixing bowl, cream together the softened butter and sweetened condensed milk until smooth and well combined.
Step 3: Gradually add the all-purpose flour, 1 cup of powdered sugar, chopped nuts, vanilla extract, and salt to the butter mixture. Mix until just combined. Be careful not to overmix; you want the dough to be soft and cohesive.
Step 4: Using your hands, scoop out about 1 tablespoon of dough and roll it into a ball. Place the dough balls on the prepared baking sheet, spacing them about 2 inches apart.
Step 5: Bake in the preheated oven for 12-15 minutes, or until the bottoms are lightly golden. The tops should remain pale.
Step 6: Allow the cookies to cool on the baking sheet for about 5 minutes before transferring them to a wire rack to cool completely. Once the cookies are cool, roll them in powdered sugar until fully coated. For an extra touch, you can roll them again right before serving to refresh the coating.