To make a delicious French vanilla ice cream, simply eliminate the Grapenuts, the raisins, and the extra ¾ cup milk.
In a small bowl, pour ¾ cup milk over raisins. Stir well, then cover and refrigerate.
In a saucepan, bring cream and remaining milk to a simmer, then remove from heat. Meanwhile, beat egg yolks with sugar until pale and fluffy, about 3 minutes. Pour ½ cup of the hot cream-milk mixture into the egg mixture, whisking as you go, then transfer it all back into the pot to create a loose custard. Heat the custard over medium heat, stirring constantly, until it reaches 175° on an instant-read thermometer (this is the point at which it will thicken noticeably). Remove from heat, add salt and vanilla extract, and pour through a strainer into a bowl. Stir in Grapenuts, then place in refrigerator to chill 6 to 12 hours.
Once mixture has finished chilling, it should register between 35° and 40° on an instant-read thermometer. Remove the now-plumped raisins from the refrigerator and stir them into the custard, discarding any extra milk. Pour mixture into ice-cream maker, leaving ¾ inch at the top to allow for expansion, and prepare according to freezer instructions.