In a large mixing bowl, cream the butter and sugar with an electric mixer for 2 minutes. Scrape down the bowl. Mix for another 2 minutes. Beat in the egg and vanilla. Beat until well combined.
In a separate bowl, sift together baking powder and flour. Add the flour mixture 1 cup at a time to the butter mixture at the lowest speed possible. Mix in the last cup of flour by hand.
Divide the dough into 2 portions and place on top of non-stick baking paper. Place another paper on top of the dough and roll out the dough to 1/8-inch thick.
Either refrigerate or freeze the dough until chilled.
Cut the cookies with desired cutter, working quickly while the dough is still chilled. Place cookies on a parchment lined cookie sheet. Re-roll scraps and refrigerate or freeze again.
Preheat the oven to 175 degrees Celcius.
Bake for 12 to 15 minutes. Remove from oven and cool.