For the Ice Cream:

Cut the cream cheese in to pieces, then add to a blender with the lemon zest, sour cream, milk, sugar, and salt. Puree until smooth.

Pour the mixture into a 1-gallon Ziploc freezer bag and submerge the sealed bag in the ice bath. Let chill until cold, about 30 minutes. While it chills, make the Raspberry Sauce.

Churn the mixture in your ice cream maker according to the manufacturer’s directions. When it’s done, transfer to a container to freeze, layering in (and then swirling around) the raspberry sauce. Freeze until firm.

For the Raspberry Swirl:

In a medium saucepan, heat the raspberries and sugar until the fruit begins to breakdown. Mix the cornstarch with the cold water until lump-free, then stir the slurry in to the raspberries.

Bring to a boil, then reduce the heat to a simmer and cook for 1 minute. Set aside to cool.