Prep: Line two baking sheets with parchment paper or silicone baking mats. Set aside.
Whisk dry ingredients: In a large bowl, whisk together the flour, baking soda, and cream of tartar. Set aside.
Cream wet ingredients: In a medium bowl, use a hand mixer to beat the softened vegan butter and sugar together until light and fluffy, about 3 minutes. Add the applesauce and vanilla extract and mix until smooth and combined.
Make the dough: Add the dry ingredients into the wet ingredients. Use a silicone spatula to fold together until the flour is just incorporated. Do not overmix.
Chill: Cover the bowl and place the dough in the refrigerator to chill for 30 minutes. While chilling, preheat the oven to 350°F (175°C). Mix together the cinnamon and sugar for the coating in a small bowl.
Roll and coat: Using a cookie scoop or your hands, form dough balls about 1.5 tablespoons each. Roll each ball in the cinnamon sugar mixture until fully coated. Place on the prepared baking sheets, spacing them a few inches apart.
Bake: Bake for 8–10 minutes, until the cookies have spread and the tops look slightly puffy. When you remove them from the oven, gently tap the baking sheet on the counter several times to help them settle and flatten slightly.
Cool: Transfer cookies to a cooling rack and allow to cool for at least 10 minutes before eating. They will continue to set as they cool.