01 - Preheat the oven to 350°F. Generously grease a 9x9-inch baking dish with butter.
02 - In a large bowl, whisk together the cottage cheese, eggs, milk, maple syrup or honey, vanilla extract, and melted butter until completely smooth and well blended.
03 - In a separate medium bowl, combine the rolled oats, baking powder, cinnamon, and salt. Stir to evenly distribute the leavening and spices.
04 - Add the dry ingredients to the wet mixture. Stir gently until just combined, being careful not to overmix.
05 - Gently fold in the blueberries, taking care not to crush them. If using frozen berries, add them directly from frozen.
06 - Pour the mixture into the prepared baking dish. Use a spatula to smooth the top evenly.
07 - Sprinkle the almonds or walnuts and coarse sugar or brown sugar evenly over the top, if using.
08 - Bake for 35 to 40 minutes, or until the center is set and the top is golden brown. A toothpick inserted in the center should come out mostly clean.
09 - Allow the bake to cool for 10 minutes before slicing into squares. Serve warm or at room temperature, optionally topped with yogurt or additional maple syrup.