Prepare the Mug: Choose a mug that is air fryer-safe. It should withstand the heat and fit comfortably inside your air fryer basket.
Mix Dry Ingredients: In the mug, combine the flour, sugar, baking powder, and ground cinnamon. Stir these dry ingredients until they are well mixed.
Add Wet Ingredients: Pour in the milk, melted butter, and vanilla extract into the dry ingredients in the mug. Mix everything thoroughly until you have a smooth batter without lumps.
Sprinkle the cinnamon sugar mixture on top.
Preheat the Air Fryer: Set your air fryer to 330 degrees F (about 165°C). Let it preheat for a few minutes.
Cook the Mug Cake: Place the mug carefully in the air fryer basket. Air fry for about 12-15 minutes. The exact time may vary depending on your air fryer model and the size of your mug.
Check for Doneness: The cake is done when a toothpick inserted in the center comes out clean or with a few moist crumbs. Be careful not to overcook; the cake will continue to cook a bit from the residual heat after removing.
Add Toppings: Once cooked, let it cool for a minute or two. Then, top with a small dollop of butter and sprinkle with cinnamon sugar for that classic Snickerdoodle flavor.
Serve: Enjoy your Snickerdoodle Mug Cake warm out of the mug.