Created by KittenCal on October 7, 2013
Step 1: Preheat oven to 350 degrees F.
Step 2: Set oven rack to middle position.
Step 3: Prepare a lightly greased baking sheet.
Step 4: In a bowl sift together flour, cocoa, baking soda and salt.
Step 5: In another bowl with an electric mixer beat together butter and both sugars until light and fluffy.
Step 6: Beat in egg and egg yolk and vanilla until well combined.
Step 7: Beat in flour mixture just until combined (the dough will be thick).
Step 8: Stir in both baking chips. If desired you can refrigerate the dough until ready to bake.
Step 9: Drop the dough by tablespoons about 2-inches apart onto cookie/baking sheet.
Step 10: Bake for 10-12 minutes, or until cookies are just set and begin to crack on top.
Step 11: Cool cookies on sheets for 2 minutes and then transfer to racks to cool completely.