Preparation Steps

• Preheat the oven to 375°F and line two baking sheets with parchment paper.
• In a skillet over medium-high heat, melt 10 tablespoons of butter, swirling occasionally until it foams and turns chestnut brown with a nutty aroma; remove from heat.
• Pour browned butter into a heat-safe bowl, including browned bits; stir in the remaining 4 tablespoons of butter until melted.
• Add dark brown sugar, granulated sugar, salt, and vanilla to the browned butter; whisk until fully incorporated.
• Whisk in the egg and egg yolk for 30 seconds. Rest the dough for 3 minutes. Repeat whisking for 30 seconds and resting 3 minutes four times total until dough is dark golden toffee color.
• In a separate bowl, whisk flour and baking soda; gradually mix into the browned butter mixture until just combined.
• Fold in the chocolate and toffee bits, reserving some for topping if desired.
• Scoop 3 tablespoon-sized portions onto baking sheets, leaving 2 inches between each cookie; optionally top with reserved bits.
• Bake for 10-14 minutes until the edges are crispy; cool completely before serving.