Preheat oven to 350 F.
Coat inside of 2-quart baking dish with butter, oil or nonstick cooking spray.
Mix oats, cinnamon, salt and baking powder.
Beat in milk, eggs, sweetpotato, butter, 1/3 cup maple syrup and vanilla extract.
Mix together, saving blueberries for last to prevent staining or crushing, and spread inside dish.
Bake 30-35 minutes until oats are tender and moisture has been absorbed.
Drizzle with maple syrup, to taste.