Preheat your waffle iron to manufactures instructions.
In the bowl of a stand mixer, whip 3 egg whites until stiff peaks form, about 4-5 minutes. Set aside.
Combine dry ingredients in a large mixing bowl and whisk together. Make a well in the dry ingredients and pour in milk, pumpkin, olive oil, egg and vinegar. Using a fork, gently beat the wet ingredients to combine then start to incorporate the dry. Once the wet and dry ingredients are fully combined, gently fold in egg whites with a spatula, careful not to mix too hard as it will deflate your egg whites.
Brush both sides of the waffle iron with a little olive oil, then add 1/4 cup to 1/3 cup of batter to the iron, or the manufacture suggests. Cook waffles as per the iron's manufacturer instructions, usually 3-4 minutes cooking time. These might take a bit longer to brown as they are already deeply coloured from the pumpkin. When they are crisp on the outside, they are done.
Serve warm with whipping cream, maple syrup, or fried chicken!