To make the blueberry purée, blend blueberries with an immersion or countertop blender until smooth. Set aside.
In a 4-quart saucepan, combine the 2 cups milk, heavy cream, prepared blueberry purée, sugar, corn syrup, and salt. Whisk to combine and place over medium heat.
While the milk mixture is heating, combine the reserved 2 tablespoons milk and cornstarch. Whisk until smooth and set aside.
Bring the milk mixture to a rolling boil and continue to boil for 1 minute. Remove from heat and slowly whisk in the cornstarch slurry. Return to heat and bring back to a rolling boil. It is essential the mixture comes back to a rolling boil to activate the thickener.
Remove from heat add the vanilla extract and dried lavender. Stir to combine and steep for 20 minutes.
Once steeped, strain to remove the lavender and pour the ice cream base into an airtight container. Cover and chill 6-8 hours. The ice cream base can be stored for up to 48 hours.
Once ready to chill, follow the manufacturer’s instructions with the ice cream maker. Churn approximately 25 minutes. Enjoy immediately as soft serve or pour into an airtight container and place in freezer for 4-6 hours for a hard serve.