Step 1

In a wide shallow pan combine blueberries, sugar, cardamom (if using), and water. Heat over a medium flame, simmering until blueberries soften and begin to burst open, about 5 minutes. Mash blueberries with a potato masher. Continue to cook until mixture thickens to the consistency of a sauce, about 5 - 10 minutes. Allow to cool 15 minutes.

Step 2

In a large bowl, preferably with a pour spout, measure out cold milk and cream. Stir in cooled blueberry sauce. Refrigerate 1 hour or more to cool completely. It's completely normal if the mixture separates while cooling.

Step 3

Process ice cream in an ice cream churn according to the manufacturer's instructions.

Step 4

Transfer ice cream to a freezer safe container and freeze until solid. About 8 hours.