Gather all ingredients and allow the egg and coconut oil to reach room temperature—this ensures better emulsification and a more cohesive dough. While ingredients warm, whisk together the flour, baking soda, salt, and cinnamon in a small bowl. I like to use freshly ground cinnamon here because it has a noticeably brighter, more complex flavor than pre-ground, and it really elevates these simple cookies. Set the dry mixture aside.

In a large bowl, whisk together the cane sugar, coconut sugar, melted coconut oil (cooled), room-temperature egg, and vanilla extract for about 30 seconds until well combined and slightly emulsified. The mixture should look creamy and uniform. Add the dry ingredient mixture from Step 1 and mix on low speed or by hand with a wooden spoon until just combined—don't overmix, as this can lead to tough cookies. The dough should come together easily without any visible streaks of dry flour.

Gently fold the old-fashioned rolled oats, raisins, and finely chopped walnuts into the dough using a spatula or wooden spoon. I prefer to chop the walnuts fairly fine so they distribute evenly throughout the cookies and don't create dry pockets. Use a folding motion rather than vigorous mixing to keep the dough tender. Make sure the oats, raisins, and nuts are evenly distributed throughout before moving to the next step.

Scoop the dough into portions of about 1½ to 2 tablespoons each and place them onto a parchment-lined plate or small tray. Space them out slightly so they're not touching. Refrigerate for at least 1 hour—this resting time allows the flavors to meld and helps prevent the cookies from spreading too much during baking, resulting in thicker, chewier cookies. While the dough chills, preheat your oven to 350°F and line a baking sheet with parchment paper.

Remove the chilled dough balls from the refrigerator and arrange them on the prepared baking sheet, spacing them 2 to 3 inches apart to allow for gentle spreading. Bake at 350°F for 11 to 12 minutes—the cookies should be golden around the edges but still slightly soft in the center. Let the cookies cool on the baking sheet for about 5 minutes (they'll continue to set as they cool), then transfer to a wire rack to cool completely. This brief cooling on the pan helps them firm up without becoming brittle.