This recipe is designed for an 8 x 8-inch baking dish or a similar-sized pan. If you're using a 9 x 13-inch pan, simply double all the ingredients.
If using frozen blueberries instead of fresh, make sure they are fully thawed and any excess liquid is drained before adding them to the recipe. I recommend fresh blueberries for best results, but frozen can be a good substitute when fresh aren't available—just be sure to mix in an extra tablespoon of both flour and sugar to account for the added moisture.