Combine the flour, sugar, baking powder, baking soda, cinnamon, nutmeg, and salt in a large mixing bowl, whisking until well mixed.
Place the spinach in a blender or food processor along with the buttermilk and egg, blending until the spinach is finely chopped and the mixture is smooth.
Pour the pumpkin puree and melted butter into the spinach mixture and blend briefly to combine evenly.
Pour the wet mixture into the dry ingredients, folding gently until just combined; do not overmix to keep the batter fluffy.
Preheat a non-stick skillet or griddle over medium heat and lightly grease if necessary.
Pour 1/4 cup portions of batter onto the hot skillet, allowing space for spreading.
Cook until bubbles form on the surface and the edges look set, about 2-3 minutes, then flip and cook for another 2 minutes until golden brown.
Transfer cooked pancakes to a plate and repeat with remaining batter, adjusting heat as needed to prevent burning.
Serve the pancakes warm, topped with your favorite syrup, additional spinach, or a dusting of powdered sugar.
