Step 1

Preheat oven to 350°F. Lightly coat a 9-by-13-inch baking dish with cooking spray.

Step 2

Combine blueberries, brown sugar and lemon zest in the prepared baking dish.

Step 3

Stir cake mix, milk, oil, butter and lemon juice together in a medium bowl. Spread the batter over the berry mixture. Bake until golden on top and firm to the touch, about 40 minutes. Let cool for 10 minutes before serving.