1. Start by browning the butter. In a medium saucepan, melt the butter over medium heat, swirling the pan occasionally. Cook until the butter turns a golden brown and gives off a nutty aroma, about 5-7 minutes. Transfer to a large mixing bowl and let it cool slightly.
2. Preheat your oven to 350°F and line two baking sheets with parchment paper.
3. In the bowl with the browned butter, add the brown sugar and granulated sugar. Beat until well combined and creamy.
4. Add the eggs one at a time, beating well after each addition, followed by the vanilla extract.
5. In a separate bowl, whisk together the flour, baking soda, and salt. Gradually add this to the wet ingredients, mixing until just combined.
6. Dissolve the instant coffee granules in a tablespoon of hot water and stir into the dough.
7. Fold in the toffee bits and walnuts (if using) until evenly distributed.
8. Drop spoonfuls of dough onto the prepared baking sheets, spacing them about 2 inches apart.
9. Bake for 10-12 minutes, or until the edges are golden brown. Let them cool on the baking sheet for a few minutes before transferring to a wire rack to cool completely.

One tip I’ve learned from years of baking with my abuela: always keep an eye on the cookies in those last few minutes. Every oven is different, and you want to capture that perfect balance of crispy edges and chewy centers.