In a saucepan over medium heat, melt the butter and continue cooking until it turns golden brown and has a nutty aroma. Remove from heat and let cool slightly.

In a mixing bowl, whisk together the flour, baking soda, and salt.

In another bowl, combine the browned butter, brown sugar, and granulated sugar. Mix until smooth.

Add the egg and vanilla extract to the butter mixture and mix until well combined.

Gradually add the dry ingredients to the wet ingredients, mixing until just combined.

Fold in the toffee bits and chocolate chips if using.

Preheat the oven to 350°F (175°C). Line a baking sheet with parchment paper.

Scoop tablespoon-sized portions of dough onto the prepared baking sheet, spacing them about 2 inches apart.

Bake for 10-12 minutes or until the edges are golden brown. Remove from the oven and let cool on the baking sheet for a few minutes before transferring to a wire rack.