In a saucepan combine the first three ingredients, then add the milk and egg yolks. Bring it to a slight boil over medium heat. Whisk constantly, don't be like me and get distracted or you will have chunks of cooked egg! Once it starts bubbling add the Reese's Spread. Take it off the burner, whisk for a minute then add the butter. If you get cooked egg in your pudding, push it through a sieve to get the majority of the lumps out. Place saran wrap over the pudding and chill for three hours.