Place butter and sugar in large bowl of electric mixer and beat until light in color. Add egg, milk and pandan extract. Beat to combine. Put mixer on low speed, gradually add flour, and beat until mixture pulls away from the side of the bowl. Divide the dough in half, wrap in waxed paper, and refrigerate for 2 hours.
Preheat oven to 375 degrees F.
Remove 1 wrapped pack of dough from refrigerator at a time. Scoop and roll balls of dough into balls and flatten onto baking sheets. Bake for 7 to 9 minutes or until slightly golden brown around the edges. Let sit on baking sheet for 2 minutes after removal from oven and then move to complete cooling on wire rack.