In a large, microwave-safe bowl, melt the coconut oil. Let cool.
Add the egg, honey and vanilla extract to the cooled oil. Whisk until completely combined.
Set a fine-mesh sieve over the bowl and sift in the almond flour, pushing through any clumps. You might have to do this in batches. Remove the sieve and add the arrowroot, cream of tartar, baking soda and salt to the bowl. Stir with a spatula until completely combined, with no dry bits of almond flour visible.
Chill the dough for an hour or up to 24 hours (this step isn't absolutely necessary but it'll make the dough much easier to roll into neat balls).
Heat the oven to 350°.
Line a baking sheet with parchment paper.
In a small bowl, mix the coconut sugar and cinnamon.
Using an ice cream/cookie scoop or tablespoon, scoop the dough into roughly 2-tablespoon-sized balls. Roll the balls in the cinnamon sugar mixture, then place on the parchment-lined sheet, about 2 inches apart. (The dough shouldn't stick to your hands if it's been chilled, but if it does, get your palms slightly damp with water.) No need to press the balls down. The cookies will spread somewhat as they bake.
Bake for 14-16 minutes, rotating the pan halfway through cooking time. The cookies will puff up and spread, with cracks along the top. The dough inside the cracks should look dry. Let cool completely, then enjoy!