• 8 oz (2 sticks) UNSALTED butter (cut into 16 pieces)
• 2 cups all purpose flour
• 3/4 tsp baking soda
• 1 1/2 tsp Kosher salt (use 3/4 tsp for regular table salt)
• 3/4 cup granulated sugar
• 2/3 cup brown sugar (tightly packed)
• 2 large eggs
• 2 tsp vanilla extract
• 1 cup roughly chopped semi-sweet chocolate (or chocolate chips)
• 1 cup crushed toffee pieces
• Coarse sea salt, for garnishing (optional)

Adjust oven rack to middle position and heat oven to 375 degrees.  Line 2 large (18×13) sheet pans with parchment paper.  Whisk flour and baking soda together in a medium bowl.  Set aside. 

Heat 12 tbsp of butter (reserve remaining 4 tbsp) in a 10 inch skillet over medium-heat until melted, about 2 minutes.  Continue cooking, whisking frequently until butter is dark golden brown and has a nutty aroma, about 1-3 minutes more. Remove skillet from heat and using a rubber spatula, transfer browned butter (scraping any solids that cling to the bottom) to a large heatproof bowl.  Stir in remaining butter and whisk until completely melted. Let cool to room temperature.

Add both sugars, salt, and vanilla to butter and whisk until fully incorporated.  Add eggs and whisk until mixture is smooth, with no lumps of sugar remaining, about 30 seconds. Let mixture stand 3 minutes, then whisk another 30 seconds.  Repeat this process of whisking and resting 2 more times until mixture is thick, smooth, and shiny. Using a rubber spatula or wooden spoon, stir in flour until it is just combined, about 1 minute. Stir in chocolate and toffee, and stir one more time to ensure that no pockets of flour remain.

Scoop dough into 3 tbsp balls. Tear each ball in half, to reveal craggy exteriors, then smush balls back together so the craggy part is on top.  

Bake cookies one tray at a time until they are golden brown around edges, about 11-15 minutes rotating sheet halfway through baking. NOTE: All ovens are different, so use your best judgment on bake time. I often to a “test” pan, baking only 3 cookies, so I can properly gauge bake time for a whole pan.

Transfer sheet pan to a cooling rack and sprinkle lightly with coarse salt, if using. Press crystals gently into cookies then allow to cool completely on sheet pan before serving.