Grease a very large cookie sheet; set aside. Scrape seeds from vanilla bean, if using; set aside.

In a medium bowl combine flour, baking powder, and salt; set aside. In a large mixing bowl beat eggs with an electric mixer on high speed for 1 minute. Gradually beat in sugar, beating on high speed for 1 minute. Add butter and vanilla seeds or vanilla extract; beat on low speed until combined. Beat in as much of the flour mixture as you can with the mixer. Using a wooden spoon, stir in any remaining flour mixture.

Divide dough into thirds. On a lightly floured surface, roll each third into a 14-inch-long roll. Arrange rolls 2 1/2 inches apart on the prepared cookie sheet; flatten each roll slightly to a 1 1/2-inch width.

Bake in a 325 degree F oven about 25 minutes or until firm and lightly browned. Cool on cookie sheet on a wire rack for 15 minutes.

Transfer each roll to a large cutting board. Using a serrated knife, cut each roll diagonally into slices about 1/2 inch thick. Arrange slices, cut sides down, on cookie sheet.

Bake slices in the 350 degree F oven for 10 minutes. Turn slices and bake about 10 minutes more or until crisp and lightly browned. Cool on the cookie sheet on a wire rack. Makes 48 cookies.

Nutrition facts are based on one biscotti.