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

In a medium saucepan over medium heat, melt the unsalted butter, stirring frequently until it turns golden brown and smells nutty.

Remove from heat and let it cool for a few minutes.

In a large mixing bowl, combine the brown sugar and granulated sugar. Pour in the slightly cooled brown butter and mix until well combined.

Add the eggs one at a time, beating well after each addition. Stir in the instant coffee granules and vanilla extract until fully incorporated.

In a separate bowl, whisk together the all-purpose flour, baking soda, and salt. Gradually add the dry ingredients to the wet mixture, stirring gently until just combined.

Fold in the toffee bits and chocolate chips if using.

Using a cookie scoop or spoon, drop rounded tablespoons of dough onto the prepared baking sheet, leaving space between each cookie.

Bake for 10-12 minutes or until the edges are lightly browned and the center looks set but soft.

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