In a saucepan over medium heat, melt the butter until it turns golden brown and has a nutty aroma, about 5-7 minutes. Remove from heat and let cool slightly.

In a mixing bowl, combine the brown butter, brown sugar, and granulated sugar. Whisk until smooth. Add the egg and vanilla extract, mixing until fully incorporated.

In another bowl, whisk together the flour, baking soda, salt, and instant coffee granules.

Gradually add the dry ingredients to the wet ingredients, stirring until just combined. Fold in the toffee bits.

Preheat the oven to 350°F (175°C). Line a baking sheet with parchment paper. Scoop tablespoon-sized balls 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 oven and let cool on the baking sheet for 5 minutes before transferring to a wire rack to cool completely.