01 -  Combine flour, butter, sugar, egg, salt, and vanilla extract. Mix thoroughly to form a smooth dough. 
 02 -  Press the dough evenly into a baking pan and bake at 180°C for approximately 20 minutes until golden brown. 
 03 -  Beat together the cream cheese, powdered sugar, and eggnog spice (or nutmeg). Add milk gradually to achieve a spreadable consistency. 
 04 -  Once the cookie base has cooled, spread the frosting evenly over it. Cut into squares and serve.