Combine milk, cream and sugar in a mixing bowl and stir well to dissolve the sugar. Add corn syrup, vanilla extract and salt; continue stirring until well blended. Chill at least 1 hour.
Pour mixture into ice cream machine bowl. Process according to manufacturer directions for 25 to 30 minutes or until the consistency of thick soft-serve ice cream. Churn in marshmallows, graham crackers and chocolate the last minute of churning or fold in after transferring to a storage container. Can be served freshly made or stored in a container in the freezer. The ice cream will become more solid in the freezer.
Recipe Note: The amounts in this recipe will fill one 1-quart size ice cream machine bowl. Bowl sizes may vary by manufacturer so amounts may need to be adjusted accordingly. Place a storage container in the freezer before mixing begins to help prevent melting while transferring from the machine. For firmer ice cream freeze in container for at least 4 hours. When adding ingredients you will need a container that holds at least 1-1/2 quarts.
Recipe Note: Always chill any stir-ins to be added to the ice cream.