To make the custard base, in a pot cook the cream, buttermilk, and sugar on medium low heat until warm, about 3 minutes. Do not let it come to a boil.
While the base is heating, beat the egg yolks with the vanilla. Once the base is warmed, pour 1/4 cup of the base into the beaten eggs, stir until well combined, and then pour the egg mixture into the pot.
While stirring, continue to heat on low for 3 minutes or until the base gets slightly thick. Do not let it come to a boil. It’s ready when it coats the back of your spoon. Cool covered in the refrigerator from 4 hours.
While the custard is chilling, in a pot, stir together the blueberries, lemon juice, sugar, flour, and cinnamon. On low heat, while occasionally stirring, cook the berries until the sugar has melted, and the juices are running and beginning to thicken, about 5 minutes. As the berries are cooking, gently smash some of the berries with the back of the spoon though leave some of the berries intact. Remove from the heat and chill for 4 hours.
To make the piecrust, preheat the oven to 350°F. Mix together the flour, salt, oil, and milk until well combined. Let it rest for 10 minutes and then roll out on a parchment-paper lined sheet until flat; you don’t have to worry about it being perfectly round. Poke holes in it with a fork, sprinkle the top with sugar and cinnamon and bake for 20 minutes or until brown. Place in the refrigerator to cool for 4 hours.
After everything has chilled, prepare as per your ice-cream manufacturer’s instructions. When the ice cream is done, break the piecrust into small pieces and gently stir them into the ice cream until well distributed.
To make the blueberry swirl, layer 1/3 of the ice cream into an airtight 1-quart container and with a spoon evenly dollop 1/3 of the blueberry filling over the ice cream. Repeat the process until all of the ice cream and blueberry puree is in the container. Freeze covered for at least 2 hours before serving.