Prepare the waffle iron and oven. Preheat your waffle iron to medium heat (setting 3 to 4). If you're not serving immediately, warm the oven to 175°F.
Mix the batter. In a large bowl, whisk together the pumpkin puree, milk, sugar, eggs, melted butter, and vanilla extract until smooth. Gently fold in the flour, baking powder, cinnamon, pumpkin pie spice, and salt. If using chocolate chips, stir them in carefully, avoiding overmixing.
Cook the waffles. Pour approximately ½ cup of the batter into the waffle iron, spreading it evenly. Cook for about 2 minutes or until your waffle maker indicates the waffles are ready. If not serving immediately, keep the waffles warm in the oven.
Serve. Plate the waffles while warm, and top with butter, maple syrup, or whipped cream as desired.