The best way is to add instant pudding mix and powdered sugar. It will firm up the whipped topping. It’s also a great way to add flavor. You could have lemon frosting, chocolate frosting ...

Most recipes call for about 1 cup of milk per packet of instant pudding, plus 8 ounces of whipped topping. If your frosting feels too stiff, feel free to loosen it by adding extra milk.