Preheat the oven to 375 degrees F. In a large mixing bowl beat butter with an electric mixer on medium to high speed for 30 seconds. Add sugar and baking powder; beat until combined. Beat in egg and vanilla until combined. Beat in cornmeal and as much of the flour as you can with the mixer. Stir in remaining flour, pistachios, and orange peel with a wooden spoon.

Shape dough into three 8x1-1/2-inch loaves. Place loaves 4 inches apart on a large ungreased cookie sheet; flatten slightly. Bake in the preheated oven for 20 minutes or until a wooden toothpick inserted near the centers come out clean. Cool loaves on cookie sheet for 1 hour.

Preheat oven to 325 degrees F. Transfer loaves to a cutting board. Cut each loaf into 1/2-inch-thick slices. Carefully place slices, cut sides down, on the cookie sheet. Bake in preheated oven for 8 minutes; gently turn over slices and bake 8 to 10 minutes more or until lightly browned. Transfer to wire racks and cool.

In a small saucepan, melt white chocolate and shortening. Dip the top of each cookie in white chocolate mixture and sprinkle immediately with nuts. Place on waxed paper until set. Makes about 42 cookies.