Prep your air fryer and pan: Preheat the air fryer to 320°F (160°C) for 3–5 minutes. Lightly grease a mini muffin tin or use silicone liners. Make sure the pan fits your basket.

Mix dry ingredients: In a bowl, whisk flour, baking powder, baking soda, salt, cinnamon, and sugar until evenly combined.

Mix wet ingredients: In a separate bowl, whisk the egg, buttermilk, 2 tbsp melted butter, and vanilla until smooth.

Combine gently: Add wet to dry and stir just until no dry streaks remain. The batter should be thick but scoopable. Avoid overmixing.

Fill the cups: Spoon batter into the mini muffin cups, filling each about 3/4 full. A small cookie scoop works well.

Air fry the first batch: Place the pan in the basket and cook for 7–9 minutes at 320°F (160°C), until the tops spring back and a toothpick comes out clean. Time may vary by air fryer.

Cool briefly: Let the muffins rest in the pan for 2 minutes, then transfer to a wire rack. This helps set the crumb.

Make the coating: Stir sugar and cinnamon together in a shallow bowl. Melt 2–3 tbsp butter in another small bowl.

Coat the muffins: Brush or dip the tops (or whole muffins) lightly in butter, then roll in cinnamon sugar. For a thicker coat, repeat once more.

Repeat with remaining batter: Refill the pan and cook the next batch. Serve warm.