Using a pair of scissors, make a small hole at the tip of each plastic egg. Grease the inside of each egg with cooking spray.
Into a medium bowl or measuring cup, combine Jell-O powder and ¾ cups boiling water. Whisk until powder is completely dissolved, then add ½ cup cold water and ¼ cup Cool Whip. Whisk to combine. Repeat process with remaining Jell-O flavors.
Place eggs, hole-up, in an empty egg carton. Using a food-safe syringe, fill each egg ⅓ of the way with one color. Place in refrigerator to set, 15 minutes. Fill each egg another ⅓ of the way full with another color and return to refrigerator to set, 15 minutes more. Fill eggs the rest of the way full and refrigerate 1 hour more, until completely set.
Gently open plastic eggs to unmold Jell-O eggs.
Recipe by 5* trending recipes with videos at https://food.theffeed.com/2019/03/31/jell-o-easter-eggs/