In a medium bowl, stir together all the dry ingredients. Set aside.
In a large bowl, whisk together all the wet ingredients. Whisk until well mixed.
Add the dry mixture to the wet mixture. Using a rubber spatula, stir and fold until no flour patches remain. Fold in raisins and walnuts, if using.
Cover bowl and chill in the freezer for about 20 minutes, until firm throughout. If necessary, allow to thaw at room temperature until just soft enough to scoop, but still very firm and chilled.
Using a medium cookie scoop, scoop and drop cookie dough balls onto the prepared cookie sheet, evenly spaced apart. Cookies will spread a bit. Optionally, press raisins into cookies—this will help decrease sticking when flattening the cookies. Using a spoon, flatten the cookies about half way for thick cookies; flatten considerably for just slightly thick cookies. The dough will be a bit sticky.
Bake for 12-16 minutes. Mine took 14 minutes. Allow cookies to cool on the cookie sheet for about 10 minutes (on a cooling rack). Then, using a heatproof spatula, lift cookies off the sheet and transfer directly onto a cooling rack to cool completely before storing. Storing instructions below. Enjoy!
*If using homemade oat flour, make sure to sift the flour to remove coarse bits of oats that could create grainy/crumbly cookies. Otherwise, try buying ready-made gf oat flour.Storing Instructions: Store in an airtight container at room temperature for 1-2 weeks.Freezing Instructions: store in a freezer-friendly container or bag. Keep for up to 1-3 months. Thaw at room temperature for about 10-20 minutes before enjoying. Or, warm in the microwave for about 5-10 seconds.Nutrition Information: is an estimate based on the best-selling, most common brands per ingredient. Also, it’s estimated based on 30 servings per recipe, made without optional ingredients.