This is a recipe I found ages ago on the Kraft Foods website. It's just fun! My kids love this because it looks so cool when it's finished.
I like to make this as a molded gelatin salad, so I've taken a few liberties with Kraft's recipe, but it's still pretty close. Use any flavor Jell-O you'd like. For Thanksgiving this year, we'll be using orange, lemon, and lime.
Bring one cup of water to a boil and add it to your first flavor Jell-O (3 oz size). Stir until dissolved. Add 3/4 cup cold water and stir well. Pour into bottom of Jell-O mold and refrigerate until set.
Bring three cups of water to a boil and add it to two (3 oz size) packages of Jell-O. Stir until completely dissolved. Add Cool Whip (16 oz tub) to the hot gelatin. Whisk until Cool Whip is completely melted and mixture is well blended. Allow to cool slightly and then pour over the gelatin that has already set in the mold.
Place in the refrigerator for 8 hours or overnight to allow it to set completely.