Beat softened cream cheese and peanut butter in a large bowl until smooth.
Mix in powdered sugar and vanilla until fully blended.
Whisk pudding mix with cold milk in a separate bowl for 1 minute.
Let the pudding stand 2 minutes to thicken slightly.
Fold the thickened pudding into the peanut butter mixture until combined.
Gently fold in the whipped topping until light and airy.
Stir in mini marshmallows and any optional mix-ins.
Cover and chill 30 minutes before serving for best texture.