Grease an 8 inch round cake pan or cover the inside and sides with plastic wrap and set aside.
Add 2 cups of rice kripies into 3 separate medium-size bowls and set aside.
Add 1 tablespoon of butter, 1 teaspoon vanilla extract, and 1 1/3 cup of mini marshmallows into a microwave bowl and microwave in 20-second intervals stirring in between until the marshmallows are melted.
Once marshallows are melted, continue to stirring until smooth.
Add to one of the rice Krispies bowls, then add 4 drops of icing color and mix until combined and rice Krispies obtain the desired color.
Transfer the rice krispie mixture into the cake pan pressing downward and spreading the mixture evenly throughout the bottom.
Repeat two more times following the same process with the other colors.
When your layering is complete, place the rice krispie cake in the refrigerator for 20 minutes to allow it to set.
Place the white chocolate chips into a microwave-safe bowl and melt using 15-second intervals stirring in between until cholate is completely melted.
Remove the rainbow rice krispie cake from the pan and plastic, and transfer it onto a plate.
Pour the melted white chocolate over the top.
Decorate the sides of the cake with Easter chocolate candy eggs.
Serve and enjoy!