In a heavy saucepan over medium heat, melt butter and swirl until it foams and turns golden brown with a nutty aroma.

Remove browned butter from heat and let it cool slightly while transferring it to a heat-proof bowl to stop cooking.

Stir both brown sugar and granulated sugar into the browned butter until combined and slightly glossy.

Beat in eggs one at a time, mixing well after each addition.

Add brewed coffee and vanilla extract, stirring to blend into the wet mixture.

In a separate bowl, whisk together flour, baking soda, and salt until evenly distributed.

Gradually fold the dry ingredients into the wet mixture until a thick cookie dough forms.

Gently stir in toffee bits and, if using, chopped nuts so they’re evenly incorporated.

Cover the dough and chill in the refrigerator for at least 30 minutes — this helps the cookies keep their shape while baking.

Preheat your oven to 350°F (175°C) and line baking sheets with parchment paper.

Scoop rounded tablespoons of chilled dough onto prepared sheets, spacing them about 2 inches apart.

Bake in the preheated oven until edges are golden and centers still look soft, about 10–12 minutes.

Let the cookies cool on the baking sheet for a few minutes before transferring to a wire rack to cool completely.