01 - Line a baking sheet with parchment paper. In a medium saucepan over medium heat, combine sugar, corn syrup, and water. Stir until sugar dissolves. Increase heat and cook without stirring until the mixture turns a deep golden color and reaches 300°F. Remove from heat, quickly whisk in baking soda until the mixture foams, and immediately pour onto the prepared sheet. Spread gently and let cool completely before breaking into small shards.
02 - Melt butter in a saucepan over medium heat. Continue cooking, swirling the pan occasionally, until the butter foams and the milk solids turn golden brown with a nutty aroma, approximately 5–7 minutes. Pour the browned butter into a large mixing bowl and let it cool for 10 minutes.
03 - Add the brown sugar and granulated sugar to the cooled brown butter. Beat until well combined. Add the eggs one at a time, beating thoroughly after each addition. Stir in the vanilla extract.
04 - In a separate bowl, whisk together the flour, baking soda, and salt. Gradually add the dry ingredients to the wet mixture, mixing just until incorporated. Gently fold in the chocolate chunks and honeycomb toffee pieces.
05 - Scoop the dough into 2-tablespoon balls and place them on a parchment-lined baking sheet. Chill the dough balls for at least 30 minutes or up to overnight to develop flavor and texture.
06 - Preheat oven to 350°F. Arrange the chilled dough balls 2 inches apart on a lined baking sheet. Bake for 11–13 minutes, or until the edges are golden while the centers remain slightly soft. Remove from oven and immediately sprinkle with flaky sea salt.
07 - Allow the cookies to cool on the baking sheet for 5 minutes to set. Transfer to a wire rack to cool completely.