In a small saucepan, combine the blueberries, maple syrup, and ginger. Heat over medium-high stirring frequently.
As the blueberries begin to pop, mash them with the back of a wooden spoon. Continue to cook until a thick sauce forms, about 5-7 minutes.
Let blueberries cool and transfer to blender. Puree until smooth. Place in a container in the refrigerator to chill.
In another saucepan, add all of the coconut milk except for 1/2 cup. Stir in the vanilla and sugar. Begin to heat over medium-high setting.
Pour the reserved 1/2 cup into a small bowl and sift in the cornstarch. Stir until well combined.
Add the cornstarch mixture to the saucepan and stir. Bring to a simmer and turn off the heat.
Pour the mixture into a shallow pan and cover with saran wrap so that the wrap is touching/pressed to the top of the coconut mixture. (You want to prevent the top from forming a "skin".)
Transfer the coconut mixture to the fridge to cool completely. (Several hours to overnight is best.)
Add the coconut mixture to an ice cream maker and run according to your manufacturers directions. Pour 1/2 of the ice cream into a dish, then add dollops of the blueberry mixture to the ice cream in the pan. Use a knife or fork to create swirls with the blueberry sauce,
Add the other 1/2 of the ice cream to the pan and add the rest of the blueberry sauce, swirling again with a knife or spoon. (I had some extra blueberry sauce leftover - add as much or as little as you like.)
Chill covered in the freezer until firm.
Notes
You may have some leftover blueberry sauce. Use it as a topping when serving or reserve as a sauce for pancakes.