Line a baking sheet with parchment paper and preheat the oven to 375 degrees F.
Place the oats, coconut, flaxseed, baking powder, and cinnamon into a medium bowl. Stir to combine.
Stir in the egg, sweet potato, coconut oil, honey or maple syrup, and vanilla.
Drop 1-tablespoon-size portions onto the prepared baking sheet and flatten into a circle about 1/4 inch thick. (Use wet hands to move the batter out of the measuring spoon if it's sticky.)
Bake for 16-18 minutes or until firm and lightly golden brown around the edges. Let cool and serve, topped with optional frosting.
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Notes
You can store these cookies, once cooled for 3 days at room temperature, 5 days in the fridge, or up to 3 months in the freezer stored in a zip-top freezer bag.
Greek Yogurt Icing: Mix together 1/4 cup plain whole milk Greek yogurt, 1 tablespoon honey, maple syrup, or powdered sugar, and 1/4 teaspoon vanilla extract. Place into a zip-top bag, seal, and snip off one corner. Drizzle over cookies and serve.
Gluten-free: Use certified gluten-free rolled oats.
Dairy-free: Skip the icing or use a favorite nondairy yogurt option.
Nut-free: Use additional oats in place of the shredded coconut and melted butter instead of the coconut oil. (You can also do this if you don't have coconut on hand.)
Egg-free: Omit the egg. Add 1/4 cup milk and 1/4 teaspoon baking soda.
If the batter seems too sticky to work with when you go to place the rounds onto the baking sheet, place the batter into the fridge for 10 minutes to firm up a little.
These cookies are not very sweet (though they are great with the icing). You can add 1-2 tablespoons of sugar to the batter if desired to make sweeter cookies.