1 (16 ounce) package lemon flavored Jell-O
1/2 cup boiling water
1 cup lemon juice
2 cups boiling water
1 cup lemon-lime flavored carbonated beverage
In a large saucepan, heat lemon-lime soda and lemon juice together. Place lemon gelatin in a small bowl; stir lemon juice mixture into gelatin. Pour mixture over lemon-lime soda mixture. Cover and let stand overnight.
Make lemon filling: Fill one-third of a flour tube with lemon-lime soda mixture. Pour lemon filling mixture onto prepared flour tube.
Cool on a wire rack or in a large bowl for 10 minutes. Refrigerate lemon-lime soda mixture at least 3 hours. Serve as a garnish (optional).