Heat oven to 350 degrees F. Grease and flour 9 x 5 x 3-inch loaf pan.
Sift together flour, baking powder and salt onto waxed paper.
Combine 1/3 cup sugar and vanilla bean in blender. Whirl for 1 to 2 minutes or until bean is finely ground.
Beat together butter, vanilla-flavored sugar, remaining sugar (and vanilla extract if using instead of vanilla bean), in small bowl at medium speed until light and fluffy, about 5 minutes. Add eggs one at a time; beat 30 seconds after each addition.
On lowest speed, beat in flour mixture just until blended. Scrape into prepared pan.
Bake in 350 degree F oven for 55 minutes or until wooden pick inserted in center comes out clean.
Cool in pan on rack for 10 minutes. Remove cake from pan to rack to cool completely. (Can be double wrapped and frozen for up to 2 months at this point.) To serve, sprinkle with confectioners' sugar if you wish, and slice. Makes 20 slices.