Start by heat treating the dry cake mix. This step is necessary when working with raw flour because it helps to ensure that the mix is free of harmful bacteria.Heat your oven to 350 degrees Fahrenheit and line a shallow baking sheet with parchment paper.
Sprinkle the cake mix onto the parchment, smoothing it into an even layer. Bake in the oven for 5 minutes, then allow it to cool to room temperature.
Place the cake mix in a large bowl. Add the vanilla yogurt, Cool Whip, and rainbow sprinkles. Mix with an electric mixer to combine.
Scoop the dip into a serving bowl and add extra sprinkles on top.
Notes
If you don't have Funfetti cake mix, you can substitute a white cake mix instead. Lemon, vanilla, or strawberry cake mix are also fun options.