1/2 cup sweetened condensed milk
1 ounce good white chocolate (Ghiradelli works great)
1 tbs. vanilla extract
Seeds of one vanilla bean
pinch of kosher salt
1/4 cup sour cream
1 1/4 cups very cold heavy cream
Microwave sweetened condensed milk and white chocolate in large bowl until chocolate melts. Stir at halfway point (about 30 seconds). Let cool, then stir in vanilla, vanilla bean, salt and sour cream.
In bowl of electric mixer fitted with whisk attachment, whip heavy cream at medium-high speed until it forms soft peaks, about 2 minutes. Whisk 1/3 of the whipped cream into white chocolate mixture. Fold remaining whipped cream into mixture until incorporated and no white streaks remain.
Place in airtight container with piece of plastic wrap on surface of ice cream and freeze until firm, at least 6 hours or up to two weeks. Serve with your favorite toppings.