Preheat the oven to 350°F and line two baking sheets with parchment paper. –
Combine the flour, baking soda, baking powder, salt, and cinnamon in a large bowl. In a separate bowl, whisk together the melted coconut oil, sugar, whole egg, egg yolk, and vanilla, whisking vigorously. –
Stir the wet ingredients into the dry ingredients. Stir in the oats, raisins, and walnuts, if using, folding into a tight batter. Set the dough aside for 20 minutes while the oven preheats. –
Scoop into 20 tablespoon-sized balls and roll lightly in barely damp hands to make them round. Spread out onto the prepared baking sheets and bake until puffed, golden, and a touch underbaked-looking, 10 to 11 minutes. Let cool on the pans for 5 minutes before transferring to a wire rack to cool completely.
