Instructions:

1. Preheat oven to 350ºF.
2. Grease a 9" x 12" baking pan and line the bottom of the pan with parchment paper, leaving overhang on both short sides of pan.
3. In a medium-size bowl whisk together:
• 2 cup all-purpose flour
• ¹/₄ tsp salt
4. Using a stand mixer, using the paddle attachment mix until creamed (light yellow in color):
• 1 cup butter, unsalted , room temperature
• 1 cup granulated sugar
5. Mix in:
• 1 tsp vanilla extract
• 1 egg yolk
6. Gradually add flour mixture, beating on low speed just to blend.
7. Drop tablespoonfuls of dough into prepared baking pan, spacing evenly.
8. Using moistened fingertips, press dough to form an even layer over bottom of pan.
9. Pierce dough all over with fork.
10. Bake cookie base until light golden brown, slightly puffed and edges begin to come away from sides of pan, about 30 minutes.
11. Place pan on cooling rack.
12. Immediately sprinkle over hot cookie base:
• 6 oz chocolate chips, bittersweet
13. Let it stand until chocolate softens, about 3 minutes.
14. Using small spatula, spread melting chocolate over top of cookie in thin even layer.
15. Immediately sprinkle over chocolate layer:
• ¹/₂ cup peppermint candies , finely chopped
16. In a double boiler, melt over low heat:
• 2 oz white chocolate chips
17. Remove bowl containing white chocolate from the water.
18. Using a fork, drizzle white chocolate all over the cookie.
19. Chill until white chocolate is set, about 30 minutes.
20. Using paper overhang as aid, lift cookie from pan and transfer to work surface.
21. Using large knife, cut cookie into irregular pieces.
22. Cookie bark can be made 1 week ahead. Store in refrigerator in airtight containers between layers of waxed paper or parchment paper.