In a medium saucepan, melt 4 tablespoons of salted butter over low heat, stirring gently to prevent scorching. Once melted, add a standard 10 oz bag of marshmallows along with 2-3 tablespoons of optional marshmallow creme. Stir continuously for about 5 minutes until the mixture is glossy and completely melted, ensuring no lumps remain.

Remove the pan from heat and swiftly mix in 2/3 cup of your chosen dry cake mix, ideally Funfetti for that classic flavor. Stir vigorously until the dry cake mix is fully incorporated and the mixture is smooth.

In a large mixing bowl, pour in 6 cups of crispy rice cereal. Then, add your gooey marshmallow mixture on top of the cereal. Gently fold the ingredients together using a spatula, making sure each piece of cereal is generously coated. Toss in about ½ to ¾ of the bottle of rainbow sprinkles, and mix until vibrant colors are evenly distributed.

Prepare a 9x13 inch baking dish by buttering it lightly or using cooking spray to prevent sticking. Transfer the sticky mixture into the dish, using your spatula to spread it out evenly. Press down firmly to ensure it holds its shape. Top with the remaining sprinkles for a delightful finish.

Allow the Cake Batter Rice Krispie Treats to cool and set at room temperature for about 30 minutes. Once set, slice them into squares or rectangles. Enjoy these delectable treats warm or at room temperature.