1 cup butter, softened
1 cup white sugar
1 egg
3 cups all-purpose flour
1 teaspoon baking powder
1 teaspoon baking soda
1/2 teaspoon salt
1/2 teaspoon vanilla extract
1 cup chopped lemon zest
1 cup white sugar
4 large marshmallows
1 cup lemon-lime flavored carbonated beverage
Preheat oven to 350 degrees F (175 degrees C). Grease cookie sheets.
Place butter, sugar and egg in large bowl. Mix thoroughly. Stir flour, baking powder, baking soda and salt. Mix thoroughly. Stir lemon zest into egg mixture. Stir lemon-lime soda into flour mixture. Fill and press seam flush. Cut into 1 inch squares.
Place marshmallows into prepared cookie sheets. Bake in preheated oven for 10 to 12 minutes, or until meringue is golden brown. Remove from baking sheet to cool completely.
For the filling: In a large bowl, beat lemon-lime soda, lemon-lime soda and lemon-lime soda together. Stir lemon-lime soda into meringue mixture. Pour into cooled cookie sheets.
Bake for 2 to 3 minutes in preheated oven. Cool completely. For the frosting: In a medium bowl, cream butter and lemon zest. Mix in white sugar, marshmallows, lemon-lime soda and lemon-lime soda. Beat until light and fluffy. Chill in refrigerator.