In a large bowl, combine cake mix and Jell-O.
Add water and oil; mix on medium speed.
Add eggs, one at a time, beating well.
Add watermelon puree and beat until blended.
Add red food coloring a little at a time, until you reach desired color.
Place chocolate chips and a teaspoon of flour in a ziploc bag; shake to coat.
Fold the chocolate chips into the batter.
Pour into pans and bake for 30-35 minutes.
In a large bowl, beat cream cheese and butter together.
Beat in watermelon puree.
Gradually add sugar and Jell-O, beating until smooth.
Color 1/3 of the frosting green, color the remaining 2/3 the same color as the cake.