01 - Preheat oven to 350°F and lightly grease a 9x9-inch baking dish with butter or cooking spray
02 - In a large mixing bowl, add rolled oats, chopped nuts, baking powder, cinnamon, and salt. Stir until thoroughly mixed
03 - In a separate bowl, whisk together milk, maple syrup, eggs, melted butter, lemon zest, vanilla extract, and lemon juice until smooth and well incorporated
04 - Pour the wet mixture into the dry ingredients. Stir gently with a spatula until just combined, being careful not to overmix
05 - Gently fold in the blueberries, distributing them evenly throughout the batter
06 - Pour the mixture into the prepared baking dish and spread into an even layer. Sprinkle coconut sugar or brown sugar over the top if using
07 - Bake for 35 minutes until the top is golden brown and the center is set. A toothpick inserted in the center should come out clean
08 - Let cool for 5 minutes before serving. Serve warm, optionally topped with extra milk or yogurt