01 - Preheat oven to 350°F and line two baking sheets with parchment paper.
02 - In a medium bowl, whisk together flour, baking soda, cinnamon, and salt; set aside.
03 - Using a mixer or whisk, cream the softened butter with brown and granulated sugars until light and fluffy, about 2–3 minutes.
04 - Beat in the egg and vanilla extract until fully blended.
05 - Gradually add dry ingredients into the wet mixture, stirring only until incorporated.
06 - Fold in chopped kale, rolled oats, and optional add-ins such as chocolate chips, raisins, or nuts.
07 - Drop tablespoon-sized portions of dough onto prepared sheets, spacing about 2 inches apart.
08 - Bake for 11–13 minutes until edges turn lightly golden and centers set.
09 - Allow cookies to cool on baking sheets for 5 minutes before transferring to a wire rack; best served warm.