• In the mixing bowl of a stand mixer, add the butter, sugar, and egg, and blend with the whisk attachment until smooth, and creamy. 
• Add the Vanilla, and mix until blended. 
• In a separate bowl, add the flour, and salt, and mix well to blend. 
• Add the flour mixture to the mixing bowl, and mix until blended, and smooth.  
• Place a large piece of parchment paper on the kitchen counter, and sprinkle with flour. 
• Place half of the cookie dough on the parchment paper, and with a floured rolling pin, roll the dough to 1/2 inch thickness. 
• Using a 3 inch round cookie cutter, cut out a circle, and then cut the circle in half, making 2 watermelon slices for the cookies. 
• Place on a parchment paper lined cookie sheet and bake at 350 degrees for 10 to 12 minutes, or until cookies being to turn golden brown around the edges. 
• Remove from oven to a wire rack, and cool completely.

For The Royal Icing:

• In the mixing bowl of a stand mixer, place the warm water, meringue powder, and karo syrup, and blend with the whisk attachment until completely blended and smooth. 
• Add the powdered sugar, about 2 cups at a time, and mix on low, until all the powdered sugar has been added.  Scrape down the sides of the mixing bowl as needed, and blend until the Icing is smooth and creamy. 
• Evenly divide the frosting into 4 bowls (adding about 1/4 of the Icing in each bowl). 
• In one of the bowls, add 2 teaspoons of watermelon flavored jello, and 2 drops of hot pink food coloring gel. 
• In another bowl, add several drops of lime green food coloring gel. 
• In the next bowl, add a few drops of the dark green food coloring gel.
• In the last bowl, add a few drops of the black food coloring gel.
• Place the Icing in a plastic pastry bag, (You'll have FOUR bags, one Hot Pink, one Lime Green, one Dark Green, and one Black), and snip off the very end of the bags. 
• Pipe the Lime Green Frosting in two lines, on the Rounded side of the Cookie, one on the outside, and one right at the Pink color, leaving just enough room to pipe a thin strip of the Dark Green Icing between the Lime Green piping.
• Pipe the Watermelon colored/Hot Pink Icing around the inside of the Cookies and fill in the Cookies with the Watermelon colored Icing. 
• Pipe small dots of the Black Icing all around the Rounded side of the Cookie, and using a Cookie Scribe pull the Black Icing down on the body of the Cookie, which will resemble Watermelon Seeds. 
• Allow about 1 hour for Icing to completely set. 
• Serve and Enjoy!