Lightly spoon all-purpose flour into dry measuring cups; level with a knife. Combine flour and next 5 ingredients (through cinnamon) in a large bowl, stirring with a whisk.
Combine milk, sweet potato, sugar, oil, vanilla, and egg yolks, stirring until smooth; add to flour mixture, stirring just until combined. Beat egg whites with a mixer at high speed until soft peaks form; fold egg whites into batter. Let batter stand 10 minutes.
Heat a nonstick griddle or nonstick skillet over medium-high heat. Coat griddle or pan with cooking spray. Spoon about 1/4 cup batter per pancake onto griddle or pan. Cook 2 minutes or until tops are covered with bubbles and edges look cooked. Carefully turn pancakes over, and cook 2 minutes or until bottoms are lightly browned.