Preheat the oven to 350°F and grease an 8x8-inch or similar baking dish.
In a large bowl, whisk together the mashed banana, nut butter, plant-based milk, maple syrup, and plant-based butter. Add the baking powder, cinnamon, and salt and whisk again.
Fold in the oats, ¾ cup of the pecans, and ½ cup of the blueberries. Pour the mixture into the prepared baking dish and smooth into an even layer.
Top with the remaining ½ cup of blueberries, the remaining ¼ cup of pecans, the brown sugar, and the coconut flakes.
Bake for 40 to 50 minutes, or until the topping is crisp and the middle is set. Remove from the oven and let cool for 10 minutes before serving.
Cover leftovers and store at room temperature for up to 4 days or in the fridge for up to 6 days.