Baked Blueberry Oatmeal

Preheat oven to 350° Fahrenheit. Lightly grease baking dish with butter or coconut oil. Set dish aside.
Add oats, maple syrup, cinnamon, baking powder, salt, milk, eggs, melted butter, and vanilla extract to large mixing bowl. Mix thoroughly until all ingredients are fully incorporated.
When oatmeal mixture is just combined, add blueberries and gently fold blueberries into oatmeal mixture, being careful not to overstir.
Transfer mixture into 9x13 baking dish. Gently spread oatmeal mixture out across bottom of baking dish in one even layer, making sure to press mixture into corners of dish.
Place baking dish in preheated oven. Bake oatmeal mixture 30 minutes, then check doneness. Continue baking as needed, checking doneness every 1 to 2 minutes, until top of baked oatmeal is golden brown and crisp. Bake time shouldn't exceed 45 minutes total, but times will vary from one kitchen to another.
When oatmeal is fully baked, carefully remove baking dish from oven. Let cool slightly, then slice baked oatmeal into 9 equally-sized bars. Serve warm.