Combine the raisins and rum in a nonreactive saucepan and heat to about 175°F (80°C). Remove from the heat and let the raisins macerate in the rum overnight.
Place the corn syrup in a small saucepan and bring to a boil. Whip the egg yolks for 1 minute. Gradually pour the hot corn syrup into the egg yolks while whipping constantly and continue to whip until the