Heat oven to 350°F. Lightly spoon flour into measuring cup; level off. In large bowl, combine flour, 1/3 cup sugar, baking powder and pumpkin pie spice; mix well. Add butter, molasses, eggs and egg yolk; beat until well blended and dough forms.
Divide dough in half. Shape each half into 10-inch roll; place on large ungreased cookie sheet. Press each half of dough into 10x3-inch rectangle. Brush rectangles with egg white; sprinkle with 1 tablespoon sugar. Discard any remaining egg white.
Bake at 350°F. for 20 minutes or until lightly browned. Cool on cookie sheets 15 minutes.
With serrated knife, cut each rectangle crosswise into 1/2-inch slices. Place slices, cut side down, on same cookie sheet.
Return to oven; bake 10 minutes. Turn cookies; bake an additional 5 to 10 minutes or until crisp and deep golden brown. Immediately remove from cookie sheets; place on wire racks. Cool 15 minutes or until completely cooled.
Meanwhile, melt white chocolate in small saucepan over low heat, stirring constantly. Drizzle over cooled cookies.
