3 cups whole milk
3 large eggs
1/2 cup sugar
4 oz cream cheese, softened
4 oz Spanish Mahón or Danish Fontina cheese, rind discarded and cheese
coarsely grated (1 cup)
1/2 teaspoon vanilla
Special equipment: an instant-read thermometer; an ice cream maker
Bring milk just to a boil in a 1 1/2- to 2-quart heavy saucepan.
Whisk together eggs, sugar, and a pinch of salt in a bowl, then add hot milk in a slow stream, whisking.
Pour custard back into saucepan and cook over moderately low heat,
stirring with a wooden spoon, until it registers 170 to 175°F on thermometer, 2 to 3 minutes.
Immediately pour custard through a fine-mesh sieve into a clean bowl,
then add cheeses and vanilla, stirring until cheeses are completely melted and incorporated.
Cover surface of custard with a round of wax paper and chill until very cold,
about 4 hours.
Freeze custard in ice cream maker.
Transfer ice cream to an airtight container and put in freezer to harden, at least 2 hours.
Let soften at room temperature 20 minutes before serving.
Cooks' note:
Ice cream can be made 1 week ahead.
Makes about 1 quart.