Heat oven to 350. 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 rectangle with egg white; sprinkle with 1 tablespoon sugar. Discard any remaining egg white.
Bake at 350 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.