01 -
Heat oven to 375°F. Line 12x17 inch baking sheet with parchment paper.
02 -
Whisk flour, baking soda, and salt in large bowl.
03 -
Combine melted butter, sugars, egg yolk, and vanilla. Pour into dry ingredients and mix well.
04 -
Add chocolate chips, then press dough evenly into pan, covering entire surface.
05 -
Bake 18-20 minutes until deep golden brown.
06 -
Sprinkle chopped chocolate over hot cookie. Return to oven 1-2 minutes to melt.
07 -
Spread melted chocolate evenly, add toppings if using. Cool 20 minutes, then chill 30 minutes.