Whisk flour, baking powder & salt in large bowl. In separate bowl, beat butter & sugar until smooth. Add egg, milk and vanilla. Add flour mixtureGather dough and divide in half. Flatten into 2 disks and wrap in plastic wrap. Refrigerate 4 hours or overnight.Heat oven to 350. Roll out cookie dough. Place cookie shapes on an ungreased baking sheet.Bake at 350 for approximately 9 -10 minutes depending on oven.