Preheat the oven to 355 degrees Fahrenheit (180 degrees Celcius). Line baking sheet with parchment paper.
Cookies:To a mixing bowl, using an electric mixer on highest speed, beat egg for 3 minutes until super fluffy.
To the same bowl, add melted butter, sparkling water, and vanilla extract.
Using electric mixer, mix on lowest speed until combined, about 10 seconds.
In a separate mixing bowl, whisk together ground sunflower seed meal, powdered monk fruit sweetener, baking powder, xanthan gum, and salt.
Add dry ingredients to bowl of wet ingredients. Mix together using electric mixer, being careful to not overmix.
Cinnamon Sugar Coating:On a plate using a fork, stir together cinnamon and powdered monk fruit sweetener to create coating mixture.
Using hands, roll dough into 12 equal-sized balls, rolling each in coating.
Transfer coated dough balls to prepared baking sheet.
Final Steps:Transfer pan to oven and bake for 5 minutes.
Then, remove pan from oven and, using your fingers, press down slightly to form a cookie that is about ~½-inch thick before shaping cookie edges slightly to reduce cracking.
Dust each cookie with a little more coating then return to oven until cooked through yet still soft, about an additional 3-4 minutes.
Remove pan from oven and allow cookies to fully cool and firm up.