Prep your ice cream maker. Follow your manufacturer's instructions for best results (usually in the user manual, which may also be available online). If your machine has a built-in compressor, you can make ice cream right away. Otherwise, place the ice cream bowl in the freezer for at least 24 hours before you start.
Make the blueberry sauce. In a saucepan, add the blueberries and sugar. Simmer for 10–15 minutes, until the blueberries are soft and the sugar is fully dissolved. Let cool for 10 minutes.
Mix the base. In a bowl, combine the blueberry sauce, heavy whipping cream, whole milk, vanilla extract, and salt. Whisk everything together until well blended, then cover with saran wrap - place a piece of saran wrap directly over the surface of the mixture (this will prevent skin forming). Refrigerate/chill for at least 6 hours or overnight.
Churn. Turn on the ice cream maker and make sure it's churning properly. Slowly pour the cream mixture into the stainless steel/freezer bowl and churn for 40–60 minutes.
Serve or freeze. Enjoy it immediately as soft-serve, or transfer it to an airtight container with a lid and freeze for at least 6 hours to let it firm up to the perfect scoopable texture.