1Heat oven to 350°F (325°F for dark or nonstick pans). Place paper baking cup in each of 24 regular-size muffins cups. Make and bake cake mix as directed on box for 24 cupcakes. Cool in pans 10 minutes; remove from pans to cooling rack. Cool completely, about 30 minutes.
2By slowly spinning end of round handle of wooden spoon back and forth, make deep, 3/4-inch-wide indentation in center of top of each cupcake, not quite to bottom (wiggle end of spoon in cupcake to make opening large enough).
3In small bowl, mix filling ingredients. Spoon into small resealable food-storage plastic bag; seal bag. Cut 3/8-inch tip off 1 corner of bag. Insert tip of bag into opening in each cupcake; squeeze bag to fill opening.
4In medium bowl, stir together 1 container butter cream frosting, the lemon peel and lemon juice. Frost cupcakes. Sprinkle with stars. Store loosely covered.