01 - Combine creamy peanut butter and softened cream cheese in a large mixing bowl. Beat with an electric mixer until the mixture is completely smooth and creamy, with no lumps remaining.
02 - Add powdered sugar to the peanut butter mixture. Mix on medium speed until fully incorporated and the mixture appears glossy and smooth.
03 - Gently fold the thawed Cool Whip into the peanut butter mixture using a spatula. Use light, sweeping motions to incorporate without deflating the whipped topping. Mix just until combined and airy—avoid overmixing.
04 - Distribute the mousse evenly among 6 serving glasses, bowls, or ramekins. Use a spoon to smooth the tops if desired.
05 - Refrigerate the mousse for at least 1 hour to allow it to set and develop the proper texture. For best results, chill up to 4 hours before serving.
06 - Just before serving, sprinkle with chopped roasted peanuts and chocolate shavings or mini chocolate chips if desired.