01 - Preheat oven to 350°F. Line two baking sheets with parchment paper and set aside.
02 - In a medium bowl, whisk together the gluten-free flour, cocoa powder, baking soda, and salt until evenly blended.
03 - In a large bowl, beat the softened butter with granulated sugar and brown sugar using an electric mixer until light and fluffy, approximately 2 minutes.
04 - Add the eggs one at a time, beating well after each addition. Mix in the vanilla extract and instant espresso powder until fully combined.
05 - Gradually add the dry ingredient mixture to the wet ingredients, mixing gently just until the dough comes together. Avoid overmixing.
06 - Using a spatula, fold the chocolate chips and chopped walnuts into the dough until evenly distributed.
07 - Scoop tablespoon-sized mounds of dough onto the prepared baking sheets, spacing them about 2 inches apart to allow for spreading.
08 - Bake for 10 to 12 minutes, until the edges are set but the centers remain slightly soft and appear underbaked.
09 - Let the cookies rest on the baking sheets for 5 minutes, then transfer to a wire cooling rack to cool completely before serving.