Whisk the first 5 ingredients (all dry ingredients) in a large bowl to blend.
Whisk milk, pumpkin, egg yolks, melted butter + vanilla (all wet ingredients) in a separate medium bowl to blend well.
Add liquid pumpkin mixture to dry ingredients; whisk just until smooth (batter will be thick).
Using an electric mixer, beat egg whites in another medium bowl until stiff but not dry.
Fold whites into batter in 2 additions.
Spray a large nonstick skillet with canola oil; heat over medium heat.
Working in batches, pour batter by 1/3 cupfuls into skillet. Cook until bubbles form on surface of pancakes + bottoms are brown, about 1 1/2 minutes per side.
Repeat with remaining batter, spraying skillet with oil between batches.
Serve hot with butter + syrup.