In a large coffee cup or coffee mug, add the water and instant coffee. (I added the ingredients to one 16-ounce coffee mug.) Place coffee cup or mug in a microwave, and microwave until coffee is heated through.
Stir the coffee, and place cup or mug in the refrigerator for 30 minutes; to chill.
To the cup or mug, add the chocolate syrup, half-and-half cream, plus 1-2 packets of Splenda; (I used 1-1/2 packets) stir to mix.
Add ice cubes to a tall beverage glass. Pour coffee over the ice cubes, and top it with a dollop or two of Cool Whip.