01 - Preheat the oven to 350°F. Lightly grease a 9x9-inch baking dish.
02 - In a large mixing bowl, thoroughly combine rolled oats, chopped nuts, baking powder, ground cinnamon, ground nutmeg, and salt.
03 - In a separate bowl, whisk together the milk, eggs, melted unsalted butter, maple syrup, and vanilla extract until fully blended.
04 - Pour the wet mixture into the dry ingredients and stir until just combined. Gently fold in the diced apples and optional dried fruit.
05 - Transfer the mixture to the prepared baking dish, spreading it out evenly. Bake for 35 minutes, or until the top is golden brown and the center is set.
06 - Allow to cool for 5 minutes before portioning. Serve warm, with additional milk or yogurt if preferred.