Preheat your waffle iron, as this batter will come together quickly.
In a large mixing bowl, combine the almond flour, egg, arrowroot, olive oil, maple syrup, water, baking powder, vanilla, and salt. Use a whisk to stir well, making sure to break up any clumps.
When the waffle iron is hot, grease it with spray oil, then pour 1/4 cup of the batter into the center of the waffle iron. (It's okay if it doesn't spread all the way to the edge of your waffle iron-- this amount makes waffles that will fit in your toaster.)
Cook until your waffle iron lets you know that the waffles are done, roughly 4 to 5 minutes. (This will vary based on your waffle iron-- I used a classic one; not a Belgium one for testing. If you use a thicker waffle iron, your waffles may need 6 minutes to cook.)
Use a fork to carefully remove the cooked waffle, then repeat with the remaining batter, making 5 waffles in total. Be sure to spray the griddle with oil between each waffle, to prevent sticking. Keep in mind that the waffles may look flimsy right when you remove them from the waffle iron, but they will crisp up quickly-- within 60 seconds-- when you transfer them to a plate.
Serve warm with your favorite toppings. (My family likes topping them with peanut butter most mornings, instead of syrup.)
Leftover waffles can be stored in an airtight container in the fridge for up to 4 days, or in the freezer for up to 3 months. Pop them in the toaster to reheat!
I've made these waffles without arrowroot starch, and the result is fine, but dry. My kids didn't like them as much as the version made with arrowroot starch, so keep that in mind for texture.
I use olive oil in this recipe because it doesn't turn solid the way that coconut oil does when it touches cold ingredients. I keep my eggs and maple syrup in the fridge, so I didn't want the coconut oil to clump in the batter. But, I assume any mild-flavored oil will work fine in this recipe.
For a Vegan Waffle: Omit the egg and add 2 more tablespoons of arrowroot starch. (So, use 3 tablespoons total.)