In a mixing bowl, whisk together the flour, baking powder, baking soda, cinnamon, nutmeg, and brown sugar.
In another bowl, mix the pumpkin puree, milk, egg, and melted butter until well combined.
Pour the wet ingredients into the dry ingredients and stir until just combined. Be careful not to overmix.
Heat a non-stick skillet or griddle over medium heat and lightly grease it with butter or cooking spray.
Using a cookie scoop or small ladle, pour small amounts of batter onto the skillet to make 3–4-inch pancakes.
Cook for 2–3 minutes on each side, or until golden brown and cooked through.
Serve warm with maple syrup, whipped cream, and a sprinkle of chopped walnuts.