Dissolve your first box of Jello in 1 cup of boiling water.
Separate the Jello in half, into two bowls.
Add two tablespoons of cold water to one and then put separate the bowl of Jello that you added the water to, into individual cups.
Place the cups flat in the fridge and allow to set for 30 minutes.
Make sure the cups are as flat as possible when you put it in the fridge so your layers don’t end up crooked.
After 20 minutes, add 1/3 of a cup of sour cream to the other bowl of Jello that has been sitting on your counter.
Mix until well combined. I use a whisk to get it really well mixed.
After the 30 minutes have passed and the Jello in the fridge has set up, pull the cups of Jello out and pour the bowl of Jello with the sour cream in it over top the set Jello.
Place back in the fridge for 30 minutes.
Repeat until you have all 12 layers.
I think it works best to start backwards with the rainbow, doing the darkest colors first.
Serve with a chocolate coin and some whipped cream!