Brown the butter. Place butter in a saucepan or skillet over medium-low heat and cook until melted. Once melted, increase heat to medium and cook, stirring constantly. Butter will sizzle and pop, scrape the bottom of the pan and swirl as it does. Once the sizzling and popping slows and brown flecks form, remove the butter from heat and pour into a large heatproof mixing bowl. Allow to cool until completely re-solidified before proceeding.

Preheat oven to 350F and line a baking sheet with parchment paper. Set aside.

Prepare the batter: Once butter has resolidified, add sugars and beat butter and sugar until creamy and well-combined (about 1 minute on high speed.)

Add egg and vanilla extract and beat again until combined.

In a separate bowl, whisk together flour, baking soda, and salt. Gradually stir dry ingredients into butter mixture.

Stir in toffee bits until combined.

Scoop and bake: Scoop dough by a level Tablespoon and drop onto prepared baking sheet, spacing cookies at least 2” apart. Transfer to center rack of 350F oven and bake for 10-12 minutes, cookies should be beginning to turn light golden brown.

Allow cookies to cool completely on baking sheet. While they’re still warm they’ll be a bit soft, but once cooled completely they should be crispy.