Preheat your oven to 350 degrees F (176 C) and lightly grease an 8-inch round cake pan with oil or line a standard-size muffin tin with paper liners. Set aside.
To a medium mixing bowl, add all the dry ingredients (almond flour, coconut sugar, potato starch, cocoa powder, tapioca starch, flaxseed meal, baking powder, baking soda, sea salt, and xanthan gum). Whisk well to combine.
Next, add the water, oil, and vanilla extract. Whisk thoroughly until no flour streaks remain. Pour the batter into your prepared baking pan.
Place in the preheated oven and bake for 28-32 minutes (for an 8-inch cake) or 18-20 minutes (for cupcakes), or until a toothpick inserted into the center comes out mostly clean (with only a few crumbs).
Let the cake cool in the pan for 10 minutes. To remove from the cake pan, run a dull knife around the edge of the pan to loosen the cake. Then place a plate or cooling rack on top and quickly invert. Allow to cool completely (~1 hour) before frosting and serving!
Store leftovers lightly covered at room temperature for up to 2-3 days*, in the refrigerator for 4-5 days, or in the freezer for 1 month. Cake can be baked ahead and frozen unfrosted. Let thaw completely at room temperature before serving.
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Notes
*If you choose to omit the xanthan gum, the cake won’t be as moist and will be more crumbly. *Recipe as written makes one 8-inch cake. For the photos, we used three 6-inch cake pans. If using three 6-inch pans, reduce bake time to 20-25 minutes. *We found the texture of this cake to be best when consumed within 24-48 hours. The nature of potato starch is a bit drying, so keep this in mind if making days in advance for an event or special occasion. You can reduce the amount of potato starch to 1/3 cup to keep it more moist, but it becomes a little more fragile and less fluffy. *Nutrition information is a rough estimate calculated without optional ingredients.