In a large bowl, add the entire box of Funfetti cake mix (unprepared) and 1 1/2 cups vanilla yogurt. Stir with a spoon or spatula until the dry mix is fully incorporated and the mixture is smooth and even, scraping the sides and bottom as needed.

Gently fold in 8 oz Cool Whip with a rubber spatula until no streaks remain and the dip is evenly combined, being careful not to overmix.

Transfer the dip to a serving bowl (or cover the mixing bowl), refrigerate for at least 1 hour to firm and chill, then serve.