1Heat oven to 375°F. Place paper baking cup in each of 24 regular-size muffin cups. In large bowl, stir cookie mix, butter, 3 teaspoons of the lime peel and the whole egg until soft dough forms. Drop dough by heaping tablespoonfuls into muffin cups; use fingers to flatten. Bake 12 minutes. Cool in pans on cooling racks.
2In medium bowl, beat egg yolks, condensed milk, lime juice and food color with electric mixer on medium speed about 1 minute or until well blended. Pour evenly into partially baked crusts, filling each about three-fourths full.
3Bake 12 to 14 minutes or until edges are set and centers are still soft. Cool 20 minutes. Cover; refrigerate until chilled, at least 2 hours but no longer than 2 days. Stir remaining 1 teaspoon lime peel into frosting. Frost cupcakes. Garnish with graham cracker chunks. Store covered in refrigerator.