01 - Preheat the oven to 350°F (175°C) and lightly grease a 9x9-inch baking dish with butter or oil.
02 - In a large mixing bowl, stir together rolled oats, chopped nuts, baking powder, ground cinnamon, ground nutmeg, and salt until evenly mixed.
03 - In a separate bowl, whisk together milk, eggs, melted butter, maple syrup, and vanilla extract until smooth and well combined.
04 - Pour wet ingredients into the bowl with the dry mixture and stir until fully incorporated. Gently fold in diced apples and dried fruit.
05 - Transfer the oat mixture into the prepared baking dish and spread into an even layer.
06 - Bake in the preheated oven for about 35 minutes, or until the top is golden brown and the center is set.
07 - Allow to cool for 5 minutes before slicing. Serve warm, with extra milk or yogurt if desired.