1. Preheat oven to 375 degrees Fahrenheit with the rack in the center of the oven.  
2. In the bowl of a mixer, add the room temperature butter and beat it on medium for 30 seconds. Slowly, add the sugar and beat at medium speed until creamy, about 3 minutes.  
3. Add the egg and the vanilla. Beat for 30 seconds. It will appear broken- it isn’t. Scrape down the bowl with a spatula and stir until it comes together. Bear for another 30 seconds or so on medium.
4. Add the flour, salt and baking powder to a bowl and whisk it together to incorporate all of the ingredients.  
5. With your mixer on low, add the flour, a little at a time, scraping down the bowl at least once during this process. Once the flour is fully incorporated, increase the speed a bit for about 15 seconds. The dough should be in a ball at this point. Make certain all of the flour is incorporated. 
6. Turn the flour out onto a piece of parchment paper which has been lightly floured. Flour the dough and a rolling pin. Shame the dough into a rectangle using your hands and then roll it out to 1/4-inch thickness.  
7. Slide the parchment onto a baking sheet and place in the refrigerator to chill for 15 minutes.
8. Prepare another baking sheet with parchment paper.  
9. Transfer the parchment paper with the dough back to your counter. Cut cookies using your favorite cutter- be sure to flour them lightly before each use. Place cookies on the prepared baking sheet lined with parchment paper- about 1/2 -inch apart. You can re-roll the scraps and repeat the process.  
10. Bake at 375 for 8-10 minutes or until golden brown around the edges. Transfer to cool on a wire baking rack for at least 1 hour before you decorate them.   

NOTE: These cookies should not be brown on the top. They are done when the sides are slightly golden in color. 

To Decorate: I always use royal icing made with meringue powder. You can usually find it at Hobby Lobby, Michaels, Wal-Mart or wherever they sell baking supplies. I simply follow the instructions and recipe on the package. I do find that gel color works better than any other kind of color- you need less and it is more vibrant...BUT note that it absolutely will stain EVERYTHING you touch so be certain to cover up your beautiful white countertops with craft paper before using it.