01 - Preheat oven to 350°F. Line two baking sheets with parchment paper.
02 - Melt butter in a medium saucepan over medium heat. Continue cooking, swirling often, until butter foams, turns golden brown, and smells nutty, about 5-7 minutes. Immediately pour into a large mixing bowl and let cool for 10 minutes.
03 - Whisk together flour, baking soda, and salt in a separate bowl.
04 - Add brown sugar and granulated sugar to the cooled brown butter. Mix until well combined.
05 - Beat in eggs one at a time, then add vanilla extract and mix until smooth.
06 - Gradually stir in the dry ingredients until just combined.
07 - Fold in chocolate chips and toffee bits.
08 - Scoop dough into 2-tablespoon portions and place 2 inches apart on prepared baking sheets.
09 - Bake for 10-12 minutes, or until golden around the edges but still soft in the center.
10 - Let cookies cool on the baking sheet for 5 minutes, then transfer to a wire rack to cool completely.