Prepare an ice bath; set aside. In a small saucepan, bring milk, cream, corn syrup, lemon juice, and sugar to a boil, about 5 minutes. Transfer to medium bowl, and place over ice bath 5 minutes.Advertisement
In another bowl, whisk mascarpone, fromage blanc, and creme fraiche. Slowly whisk milk mixture into cheese mixture. Strain through fine sieve into a large bowl. Cover, and chill in refrigerator at least 1 hour, or overnight.
Freeze in an ice-cream maker according to manufacturer's directions.