This is great served over vanilla ice cream.
Heat chocolate and milk in microwave for 30 seconds; stir. Heat an additional 30 to 60 seconds, remove, and stir until melted. Add peanut butter, corn syrup, and vanilla and stir until creamy. If necessary, heat for another 30 seconds in the microwave.
Pour over ice cream. Can be stored in the refrigerator in an airtight container for up to 2 weeks.