Sift together flour, sugar, baking powder and salt in a large mixing bowl. In small bowl, whisk together the milk, orange juice, oatmeal, egg yolks and butter; stir to combine. Add orange juice mixture to flour mixture; stir gently just until combined.
In clean mixing bowl, beat egg whites with mixer until soft peaks form. Add vanilla extract. Gently fold egg whites into flour mixture, being careful not to overmix.
Heat large skillet over medium-high heat for 5 minutes. Grease bottom of skillet with small amount of melted butter or vegetable oil. Use large spoon to drop hockey puck-sized dollops of batter in skillet. Cook until bubbles start to form on top of the pancake; flip with spatula and cook 2 more minutes, or until golden brown. Remove from skillet and keep warm; repeat with remaining batter. Serve immediately.
Serving Suggestion: Cut pancakes in fun shapes with cookie cutters.