Preheat oven to 350 degrees F (175 degrees C). Grease cookie sheets.
In a large bowl, cream together the butter and white sugar until light and fluffy. Beat in the egg, milk, and vanilla. Combine the flour, baking powder, and salt; stir into the creamed mixture.
Shape the dough into 1-inch balls; roll in the chopped walnuts. Place cookies 2 inches apart onto the prepared cookie sheets. Bake for 8 to 10 minutes in the preheated oven. Allow cookies to cool on baking sheet for 5 minutes before transferring to a wire rack to cool completely.
In a small bowl, mix together the confectioners' sugar and 2 tablespoons of milk. Drizzle over cooled cookies.
Interesting Facts
Krusciki are a Polish treat traditionally served on special occasions like weddings, baptisms, and Christmas.
Krusciki are usually made with walnuts, but they can also be made with other nuts and even poppy seeds.
Krusciki are a popular dessert in Poland, and they are also becoming popular in other parts of Europe.