In a small bowl, mix together the blueberries and 1 tablespoon arrowroot flour, tapioca flour, or cornstarch. Set aside.
Place almonds on a large cookie sheet and toast until fragrant, around 5 minutes. Set aside
In mixing bowl, combine the almond flour, tapioca, cinnamon, nutmeg, soda, oats, xanthan gum, and salt.
In a large mixing bowl, beat the shortening and palm sugar until combined.
In a separate bowl, whisk together the egg, agave or honey, lemon juice, and vanilla.
Add the egg mixture to the sugar/shortening mixture, and beat to thoroughly combine.
Add the flour mixture and stir until well combined.
Fold in the blueberries and almonds.
On a well greased or parchment lined baking sheet, form batter into small rectangles and place at least 2 inches apart.
Bake 9-12 minutes, or until browned.
Cool completely on wire rack.
Notes
The recipe below is for a copycat Oat Blueberry Lemon Bar. But you can use any add-ins you'd like... chocolate chips, nuts, coconut, various fresh or frozen fruits, etc.
I add a Tbsp. of starch only when using fresh or frozen fruit to help soak up the excess liquid. If not using fresh or frozen fruit, you can omit the extra Tbsp. of starch.
I have only tested this recipe with non-hydrogenated shortening. While I would imagine butter or coconut oil would work, I can't guarantee the results.
Store leftovers covered at room temperature for 1 to 2 days or can be frozen.