Pumpkin Pancakes

1 1/4 cups unbleached all purpose flour
3 tablespoons sugar
2 teaspoons baking powder
1 1/4 teaspoons pumpkin pie spice
3/4 teaspoon salt
1 1/3 cups whole milk
3/4 cup canned pure pumpkin
4 large eggs, separated
1/4 cup (1/2 stick) unsalted butter, melted
1 teaspoon vanilla extract
Vegetable oil
Maple syrup

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