01 - 
                In a medium bowl, whisk together flour, brown sugar, baking powder, pumpkin pie spice, and kosher salt until thoroughly mixed.
              
              
              
                02 - 
                In a separate bowl, stir pumpkin puree, egg, whole milk, vanilla extract, and melted butter until smooth and uniform.
              
              
              
                03 - 
                Gently fold dry ingredients into wet ingredients using a spatula, mixing just until no dry flour remains to ensure tender texture.
              
              
              
                04 - 
                Using a spoon or small cookie scoop, portion batter into evenly sized small rounds and place on a parchment-lined or lightly greased baking sheet for transfer.
              
              
              
                05 - 
                Preheat air fryer to 360°F (182°C) for several minutes to achieve optimal cooking temperature.
              
              
              
                06 - 
                Arrange donut holes in a single layer with space between to allow air circulation; cook in batches for 8 to 10 minutes or until golden brown and puffed, then remove while hot.
              
              
              
                07 - 
                Brush each hot donut hole with melted butter on all sides, then roll gently in a cinnamon and granulated sugar mixture to adhere a sweet, spiced coating.