Preheat the oven to 350°F. Line a standard muffin tin with cupcake liners or spray with non-stick spray.
In a large bowl, mix together the cake mix, water, oil, and egg whites until smooth.
Split the batter evenly between two bowls. In one bowl, mix in the lime jello powder. Leave the other bowl as is for a fun contrast of color.
Layer the green and white batters into your cupcake liners, go green first, then white, then green again until each cup is about 2/3 full.
Bake for 18–20 minutes or until a toothpick comes out clean. Let them cool completely before frosting.