# Step-by-Step Instructions:
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.