In a large mixing bowl, combine the strawberry gelatin powder, powdered sugar, vanilla extract and milk using a handheld or standing mixer. Beat on medium high for about a minute and a half, the mixture will thicken a bit.
Set in the fridge for about 1 hour to help the strawberry mixture cool and set up some. It won’t be as firm as actual jello, it will be more like a thick glaze.
Next, take the strawberry gelatin mixture out of the fridge and beat in one tub of Cool Whip until it's mostly incorporated. Repeat the same process with the second tub of Cool Whip, until well combined.
Your Cool Whip should become stiffer as you beat it and stand up into peaks on the whisk attachment.
You can use the strawberry cool whip right away or store it in the refrigerator until you're ready to use it. If you're not using it immediately, be sure to cover it to prevent it from drying out. The longer the frosting is in the fridge, the better it will set up - I recommend chilling for 1 hour at least if you are piping.
*Important Notes: I recommend only using the brand name Cool Whip. I have tried generic brands of cool whip before and they just don’t work as well. ALSO, be sure the cool whip is not at all frozen. It must be fully thawed or when you go to whip the ingredients together, the consistency will be wrong and won’t stiffen up properly.
*What to use it on: I pipe this cool whip onto cupcakes, ice entire cakes and use it as a topping on frozen strawberry drinks! You can even dip fruit in it!