Step 1

Combine blueberries and sugar in a large saucepan over medium heat. Bring to a boil. Cook until blueberries become soft and start to release their juices, about 10 minutes.

Step 2

Combine the lemon juice and cornstarch. Pour into the blueberries.

Step 3

Stir in the cinnamon.

Step 4

Continue to simmer until the juices begin to thicken, approximately five minutes.

Step 5

Remove filling from the heat. Pie filling will continue to thicken as it cools.