1. In small bowl, combine rum and chopped mint. Set aside.
2. Heat oven to 350° F. Lightly spray 13×9-inch pan with cooking spray. In large bowl, mix butter and 1/2 cup powdered sugar together with electric mixer on medium speed. Mix in 1 3/4 cup of the flour on low speed, just until well combined. Press in pan. Bake 22 to 25 minutes or until set and lightly browned.
3. Meanwhile, in large bowl, mix eggs and sugar, with whisk. Add remaining 1/4 cup flour and salt, mix with whisk until blended. Mix in lime peel, lime juice, food color and milk.
4. Place strainer over medium bowl; pour rum mixture into strainer. Press mixture with back of spoon through strainer to drain liquid from leaves; discard leaves. Mix strained liquid into egg mixture, with whisk until well combined. Pour over partially baked crust. Bake 25 to 27 minutes longer or until center is set.
5. Cool completely, about 1 hour. Sprinkle with powdered sugar. For bars, cut into 6 rows by 4 rows. Store bars, tightly covered, in the refrigerator.