01 - Preheat the oven to 350°F and line two baking sheets with parchment paper.
02 - In a medium bowl, whisk together the gluten-free flour, baking soda, salt, and espresso powder. Set aside.
03 - In a large bowl, beat together the softened butter, coconut oil, brown sugar, and granulated sugar until creamy and light, about 2-3 minutes.
04 - Add eggs one at a time, beating well after each addition. Stir in vanilla extract.
05 - Gradually mix in the dry ingredients, stirring until just combined.
06 - Fold in the chocolate chips and chopped walnuts.
07 - Scoop tablespoon-sized mounds of dough onto the prepared baking sheets, spacing them about 2 inches apart.
08 - Bake for 11-13 minutes or until edges are golden and centers are just set.
09 - Cool on the baking sheet for 5 minutes, then transfer to a wire rack to cool completely.