Preparation

• In a medium stainless steel sauté pan set over medium heat, melt the butter. Swirl the pan occasionally until it becomes foamy. Cook until brown bits form at the bottom, then pour into a mixing bowl.
• Add the granulated sugar and brown sugar to the hot butter, stirring to combine. Set aside to cool to room temperature.
• In a medium bowl, combine the flours, baking soda, baking powder, salt, and espresso powder.
• Whisk in the eggs, yolk, and vanilla to the cooled butter mixture until combined. Gradually stir in the flour mixture with a rubber spatula, followed by the chocolate chunks and toffee bits.
• Wrap dough in plastic wrap and refrigerate for at least 24 hours but no more than 72 hours.
• Let dough sit at room temperature for about 1 hour until soft enough to scoop.
• Preheat the oven to 350ºF and line baking sheets with parchment paper.
• Divide the dough into 3-tablespoon sized balls using a large cookie scoop and drop onto prepared baking sheets.
• Optionally, portion the dough, freeze until solid, then store in an airtight container for up to 6 weeks.
• Bake for 12 to 14 minutes or until golden brown. Sprinkle flaky sea salt on top if desired and let cookies cool for 2 minutes before moving to wire racks.
• Store in an airtight container at room temperature for up to 3 days.