Grease 8 or 9 inch round cake pan and pour in batter. Bake in preheated oven for 25 minutes, or until a toothpick inserted into center of pie comes out nearly clean. Let cool for about 5 minutes before unmolding.
In small saucepan, place 1/3 cup water, blueberries, maple syrup or honey, lemon zest, and a pinch of salt. Bring to a boil, reduce heat to medium-low, and simmer for 5 minutes. In small bowl, stir cornstarch or arrowroot powder into 1 Tbsp water until dissolved. Pour into blueberry mixture and stir. Simmer for another 3 minutes, or until mixture thickens.