Preheat and prep: Heat oven to 350°F (175°C). Line two baking sheets with parchment paper.
Whisk dry ingredients: In a medium bowl, mix 1 cup whole wheat pastry flour, 1 teaspoon ground cinnamon, 1/2 teaspoon baking soda, and 1/2 teaspoon fine sea salt.
Stir in 1 1/2 cups rolled oats.
Combine wet ingredients: In a large bowl, whisk 1/3 cup melted, cooled coconut oil (or olive oil), 1/4 cup maple syrup, 1/4 cup light brown sugar, 1 large egg, and 2 teaspoons vanilla until smooth.
Bring it together: Add the dry mixture to the wet and stir just until no dry streaks remain. Fold in 1/2 cup raisins and 1/3 cup dark chocolate chips. If using, add 1/4 cup chopped nuts.
Rest the dough: Let the dough sit for 10 minutes.
The oats will hydrate, making the cookies thicker and chewier.
Scoop and shape: Scoop heaping tablespoons onto the sheets, spacing 2 inches apart. Gently flatten the tops with your fingers for even baking.
Bake: Bake 9–11 minutes, until edges are set and centers still look slightly soft. Do not overbake.
Cool: Let cookies rest on the sheet for 5 minutes, then transfer to a rack to cool completely.
They firm up as they cool.