mix dry ingredients: in a large mixing bowl, whisk together the flour, baking powder, baking soda, ground cinnamon, ground nutmeg, and brown sugar.
mix wet ingredients: in a separate, medium bowl, mix together the pumpkin puree, milk, lightly beaten egg, and melted butter until well combined.
combine wet & dry: pour the wet pumpkin mixture into the dry ingredients. stir with a spatula until just combined. do not overmix! a few lumps in the batter are perfectly fine and are the secret to tender pancakes.
rest the batter (important!): let the batter rest at room temperature for at least 10 minutes (up to 15 is great). this step allows the baking powder to activate and create bubbles, which makes these thick pancakes much lighter and fluffier.
preheat skillet: heat a large non-stick skillet or griddle over medium-low heat. lightly grease it with butter or cooking spray. a lower heat is essential to cook the center of these dense pancakes without burning the outside.
cook mini pancakes: using a 1.5 tablespoon cookie scoop or a small ladle, pour small amounts of batter onto the hot skillet. aim for mini pancakes about 3 inches in diameter.
flip: cook for 2-3 minutes, or until bubbles form on the surface and the edges look set. flip carefully and cook for another 2-3 minutes on the other side, or until golden brown and cooked through.
serve: serve the mini pumpkin pancakes warm with a drizzle of maple syrup, a dollop of whipped cream, and a sprinkle of chopped walnuts.