With electric mixer, beat butter thoroughly.
Add sugar gradually, continuing to beat about 5 minutes until light and fluffy
Add egg and vanilla and mix well
Lightly spoon flour into a cup and level off - thoroughly mix with salt and baking powder
Add to mixing bowl ⅓rd at a time and mix well between additions - dough will be stiff
Load cookie gun and squeeze out rows of cookie on a parchment lined cookie sheet
Cut rows into 2" sections with a sharp metal spatula
Bake at 375*F until just starting to turn light golden around the edges - about 12 minutes. Do not over cook