In a medium bowl, stir together the flour, baking powder and salt, and set aside.
In the bowl of an electric mixer, using the paddle attachment, cream together the butter and sugar until light and fluffy. This should take 2-3 minutes.
Add the egg and vanilla and beat another minute or so.
Add the flour mixture slowly. (Be careful not to add too much at a time or you will have a snowstorm of flour.)
Blend until all of the flour is incorporated. The mixture will look crumbly at first but just keep blending until the dough begins to pull away from the sides of the bowl.
Remove about half of the dough from the bowl and knead by hand just a bit to form a smooth ball. Roll out dough onto a lightly floured work surface, or onto a piece of plastic wrap (as described in detail in the blog post above).
Cut out cookies into desired shapes and place entire baking sheet of unbaked cookies into the freezer for 5 minutes.
Preheat oven to 350°F and bake cookies in preheated oven for 9-11 minutes, depending on the size and thickness of your cookies.
The cookies are baked when then are no longer shinny on top, but they will not show much of any change in color.
Cool on baking sheet just a minute or so, then carefully move to a wire cooling rack and allow to cool fully before decorating.