Prepare your waffle iron by preheating it according to the manufacturer’s instructions. Lightly spray with non-stick cooking spray if needed.
Combine the dry ingredients in a large mixing bowl: flour, baking powder, salt, sugar, and pumpkin pie spice. Whisk thoroughly to ensure even distribution of the spices.
In a separate bowl, mix the wet ingredients by whisking together the pumpkin puree, plant milk, melted oil, apple cider vinegar, and vanilla extract until smooth and well incorporated.
Pour the wet mixture into the dry ingredients and gently fold together with a spatula until just combined. Some small lumps are okay—overmixing will make your waffles tough. The batter should be thick but pourable.
Let the batter rest for 5 minutes while your waffle iron continues heating. This allows the baking powder to activate and the flour to hydrate properly.
Scoop about 1/2 cup of batter (or the amount recommended for your waffle iron) onto the center of the preheated iron. Close the lid and cook until the steaming stops and the waffle is golden brown, approximately 4-5 minutes.
Carefully remove the waffle using a fork or silicone tongs to avoid scratching your waffle iron. The waffle should be crisp on the outside but still tender inside.
Repeat with remaining batter, adjusting the amount if needed based on your first waffle. Keep finished waffles warm in a 200°F oven on a baking sheet if serving all at once.
Serve immediately with your choice of toppings. A drizzle of warm maple syrup and a dollop of vegan butter are traditional, but feel free to get creative!