Whisk together pancake mix, granulated sugar, powdered sugar, and baking powder in a large bowl. Add milk and 2 egg yolks; whisk just until combined. Set pancake batter aside.

Beat 4 egg whites and vanilla in a large mixing bowl with an electric mixer on high until stiff peaks form (tips stand straight). Fold egg whites into pancake batter just until combined; do not overmix. Fold in ½ cup jimmies.

Heat a large nonstick skillet over medium-low heat. Place 2 (3×2⅛-inch) metal rings in skillet, with bottoms of rings resting flat in skillet. Spray rings with nonstick spray. Fill each ring with ¾ cup batter. Pour ¼ cup water in skillet outside of rings.

Cover skillet and cook 15 to 18 minutes or until tops spring back. Turn over pancakes in metal rings. Cook, covered, 3 minutes more. Remove pancakes from skillet. Using a narrow metal spatula or table knife, loosen sides of pancakes from rings. Remove pancakes from rings; transfer to a serving plate. Repeat with remaining pancake batter and ¼ cup water for steaming.

To serve, garnish pancakes with whipped topping, berries, and additional jimmies, if desired.