Combine flour, sugar, and salt. Add egg yolks and milk; stir until dough leaves sides of bowl.
Turn dough out onto a lightly floured surface; knead 10 to 12 times or until smooth. Roll dough to 1/8-inch thickness; cut into 3-inch squares. Fold each square in half, and make 4 slashes on the side parallel to the folded edge.
Carefully drop each pastry square into deep hot oil (370°); cook only a few at a time. Fry until golden brown. Drain well. Sprinkle with powdered sugar.