Preheat oven to 350 degrees.
Toast 3/4 cup pecan halves for 6 minutes until fragrant. Let cool then finely chop.
Cream butter and sugar. Add egg yolk and vanilla and beat until light and fluffy.
Whisk flour, baking powder, cinnamon and the cooled finely chopped pecans. Stir dry ingredients into the creamed mixture. Mix until well combined. Press into a greased 13x9 pan. Brush lightly with lightly beaten egg white. Coarsely chop remaining 1/2 cup pecans and sprinkle over top of bars.
Bake at 350 degrees for 30 minutes or until golden brown. Transfer to wire rack for 5 minutes to cool. After 5 minutes cut into 15 bars, but keep in pan. After bars have cooled remove from pan onto wire rack.
Put chocolate chips in a microwave safe bowl. Microwave at 50% power for 1 minute. Stir, then continue to cook at 20 second intervals until chocolate is smooth. Drizzle chocolate over cooled bars. Bars can be stored in airtight container for several days.