01 - Preheat oven to 350°F (175°C) and grease a 9x9-inch baking dish to prevent sticking.
02 - In a large mixing bowl, blend rolled oats, chopped nuts, baking powder, ground cinnamon, ground nutmeg, and salt until well distributed.
03 - In a separate bowl, whisk together milk, eggs, melted unsalted butter, maple syrup, and vanilla extract until smooth.
04 - Pour wet mixture into the bowl with dry ingredients. Stir until thoroughly combined, then fold in diced apples and dried fruit.
05 - Transfer batter to the prepared baking dish and spread evenly. Bake for 35 minutes, or until the top is golden and the center is set.
06 - Allow oatmeal bake to cool for 5 minutes before serving. Serve warm, optionally topped with milk or yogurt.