In a medium bowl, whisk together the dry ingredients: flour, brown sugar, baking powder, pumpkin spice, and salt.

Cut cold butter into small cubes and mix into the dry mixture until it resembles coarse crumbs.

In another bowl, whisk together pumpkin puree and buttermilk until fully combined.

Gently pour the wet ingredients into the dry mixture and stir until just combined, forming a shaggy dough.

Transfer the dough to a floured surface, knead gently, pat into a 4-inch square, and cut into four equal pieces.

Brush the tops of the biscuits lightly with melted butter, preheat air fryer to 350°F, and arrange biscuits in the basket.

Air fry the biscuits at 350°F for 10-12 minutes, checking periodically for even cooking.

Check for doneness by tapping the tops; they should sound hollow. Let cool slightly before serving.