Preheat your oven to 375°F and line a baking sheet with parchment paper. While the oven heats, prepare your ingredients: finely shred the zucchini and squeeze it dry in a clean kitchen towel or paper towels—this removes excess moisture that would otherwise make the cookies dense and cake-like. Bring your egg and butter to room temperature if they aren't already, as this helps create a smoother, more uniform dough. Measure out all your dry ingredients and set them aside together.

In a large bowl, beat the softened butter with both sugars for 3-5 minutes until the mixture is light and fluffy—this incorporates air and creates a tender cookie texture. You'll notice the mixture change from dense to pale and voluminous. This step is crucial for the final cookie structure, so don't rush it.

Add the room temperature egg and vanilla extract to the creamed mixture and beat until fully combined. Then add the squeezed-dry zucchini from Step 1, stirring gently just until no white streaks remain. I like to fold the zucchini in rather than aggressively beat it so it distributes evenly without breaking down further and releasing excess moisture into the dough.

In a separate small bowl, whisk together the flour, baking soda, salt, and cinnamon. Add this dry mixture to the wet ingredients from Step 3 and stir until just combined—do not overmix, as this develops gluten and makes cookies tough. Fold in the chocolate chips and walnuts until evenly distributed throughout the dough.

Drop rounded tablespoon-sized portions of dough onto the preheated baking sheet, spacing them about 4 inches apart since they will spread during baking. Bake for 9-11 minutes, until the edges are set but the centers still look slightly underdone—they'll continue to cook as they cool. I pull mine out when the edges just turn golden but the tops still look a touch moist, which keeps them tender inside.

Allow the cookies to cool on the baking sheet for 5 minutes—this lets them set just enough to handle without falling apart. Then transfer them to a wire cooling rack to cool completely. This final resting on the pan prevents them from spreading too much and ensures even baking throughout.