Prepare the Filling: In a bowl, mix the blueberries, granulated sugar, cornstarch, and lemon juice. Stir until the blueberries are evenly coated.
Grease the Crockpot: Lightly grease the inside of your crockpot to prevent sticking.
Layer the Blueberries: Pour the blueberry mixture into the bottom of the crockpot, spreading it out evenly.
Make the Topping: In a separate bowl, combine the cake mix, brown sugar, and cinnamon. Pour the melted butter over the mixture and stir until crumbly.
Add the Topping: Sprinkle the topping evenly over the blueberry mixture.
Cook: Cover and cook on high for 2-3 hours or until the topping is golden and the blueberries are bubbling.
Serve: Let cool slightly before serving with a scoop of vanilla ice cream or whipped cream.
