1 egg
2 cups milk
1/4 cup all-purpose flour
1 cup white sugar
1 teaspoon baking powder
1 teaspoon vanilla extract
1/4 teaspoon salt
1/4 cup boiling water
Beat egg yolks in small bowl in medium bowl. Stir in milk and flour. Beat with electric mixer until ingredients are thoroughly combined. Stir egg yolks into milk mixture.
Heat remaining milk in oven to 325 degrees F (165 degrees C) or until an instant read thermometer reads 140 degrees F (60 degrees C). Pour mixture over cooled cookie. Chill in refrigerator. Roll dough on lightly floured cut into small round rolls. Place cookies 2 inches apart onto ungreased cookie sheets.
Bake in preheated oven for 30 minutes or until firmly brown. Cool slightly.