Preheat oven to 350ºF (170ºC)
In a bowl with an electric mixer beat together butter, shortening, and 3/4 cup sugar until light and fluffy. With a knife halve vanilla beans lengthwise. Scrape seeds into butter mixture and beat in egg and vanilla extract until combined well.
Sift flour, baking powder, and salt into mixture and beat until just combined.
Let the dough chill for at least 30 minutes.
Make into 1 inch size balls and roll them in 1/4 cup sugar. Place them 2" apart in a cookie sheet lined with baking mat or parchment paper.
Bake for 6-8 minutes or until the edges gets lightly golden.