From Better Homes & Gardens - The Best Sugar Cookies

In a large bowl beat butter on medium to high speed for 30 seconds.
Add sugar, baking powder, and salt.
Beat until combined, scraping sides of bowl occasionally.
Beat in egg, milk, and vanilla until combined.
Beat in as much of the flour as you can with the mixer.
Using a wooden spoon, stir in any remaining flour.
Divide dough in half.
Cover; chill about 30 minutes or until dough is easy to handle.
Preheat oven to 375 degrees F.
On a lightly floured surface, roll dough, half at a time, until 1/8 to 1/4 inch thick.
Using 2-1/2-inch cookie cutters, cut dough into desired shapes.
Place cutouts 1 inch apart on ungreased cookie sheets.
Bake for 7 to 10 minutes or until edges are very light brown.
Transfer to wire racks; cool.
If desired, frost with Royal icing and/or decorate with decorative candies.