Make the cheesecake bites: Toss the graham cracker crumbs with the melted butter and 1 tablespoon sugar in a medium bowl. Divide between two 1 1/2-cup bowls or ramekins; press into the bottoms and up the sides. Put the cream cheese in the medium bowl (no need to wipe clean); stir with a spatula. Add the heavy cream, lemon juice, vanilla and remaining 2 tablespoons sugar; mix until smooth. Spoon into the prepared bowls, cover and freeze until firm, about 2 hours. Remove the bowls from the freezer and run a knife around the cheesecakes; turn out onto a cutting board and roughly chop. Cover and keep frozen until ready to use.
Meanwhile, make the blueberry sauce: Combine the blueberries, sugar, cornstarch, lemon juice and 1 cup water in a medium saucepan; bring to a simmer, stirring occasionally. Cook, stirring occasionally, gently squashing the berries as they soften, until the mixture is thick and shiny, about 30 minutes. (You should have about 1 2/3 cups of sauce; cook slightly longer to reduce if necessary.) Transfer to a small bowl and refrigerate until cold.
Make the ice cream: Put the heavy cream, cream cheese, sour cream, sugar, vanilla, lemon zest and salt in a food processor; process until very thick and fluffy. Layer the ice cream mixture, blueberry sauce and cheesecake bites in a shallow 2-quart baking dish. Cover with plastic wrap, pressing against the surface; freeze at least 3 hours. Let sit at room temperature 20 minutes before scooping.
To quickly chill your blueberry sauce, transfer to a stainless-steel bowl and set in a slightly larger bowl of salted ice water; stir until cold.