In a mixing bowl, combine the creamy peanut butter, powdered sugar, and vanilla extract. Mix well until smooth and creamy.
In a separate bowl, whip the heavy cream until soft peaks form.
Gently fold the whipped cream into the peanut butter mixture using a rubber spatula. Be careful not to deflate the whipped cream. Stop folding when just combined.
Add the milk to the mixture to adjust the texture to your liking, folding gently until incorporated.
Spoon the Peanut Butter Fluff into serving cups or bowls.
Refrigerate for at least 30 minutes to set slightly before serving.
For added flavor, you can mix in mini chocolate chips or chopped nuts before refrigerating.
Serve with sliced fruits, graham crackers, or use as a filling for pastries.