01 - Preheat the oven to 350°F. Lightly grease an 8x8-inch baking dish with butter or cooking spray to prevent sticking.
02 - In a large mixing bowl, add rolled oats, sliced almonds, ground cinnamon, ground nutmeg, baking powder, and fine sea salt. Whisk briefly to distribute the spices and leavening evenly throughout the oats.
03 - In a separate medium bowl, crack the eggs and add milk, maple syrup, melted butter, and vanilla extract. Whisk vigorously until the eggs are fully incorporated and the mixture is smooth and uniform.
04 - Pour the wet ingredients into the dry ingredients. Stir with a spatula or wooden spoon until just combined, ensuring no dry pockets remain at the bottom of the bowl. The mixture will appear slightly loose.
05 - Gently fold in the chopped dried fruit and diced apple if using. Take care not to overmix, as this can affect the final texture of the bake.
06 - Pour the batter into the prepared 8x8-inch baking dish. Use the back of a spoon or spatula to spread the mixture evenly, ensuring it reaches all corners.
07 - Place the dish in the center of the oven and bake for 35 to 40 minutes. The bake is done when the center feels firm to the touch and the top has developed a golden-brown color.
08 - Remove from the oven and let the bake rest for 5 to 10 minutes before serving. This allows the structure to set for cleaner slices. Serve warm, optionally topped with additional sliced almonds or an extra drizzle of maple syrup.