Preheat your oven to 350°F (175°C) and lightly grease a 9x9-inch baking dish with coconut oil.
In a large mixing bowl, combine the rolled oats, peeled and chopped apple, chopped walnuts, ground cinnamon, ground nutmeg, baking powder, and a pinch of salt. Mix thoroughly.
In a separate bowl, whisk together the unsweetened applesauce, maple syrup (or honey), melted coconut oil, and vanilla extract until well blended.
Pour the wet mixture into the bowl with the dry ingredients and stir gently until fully incorporated.
Transfer the mixture into your prepared baking dish, spreading it out evenly. Optionally, sprinkle extra ground cinnamon on top.
Place the baking dish in the preheated oven and bake for 30 to 35 minutes until the top is golden brown and a toothpick inserted in the center comes out clean.
Once baked, remove from the oven and allow to cool for about 10 minutes before slicing into 9 squares for serving.
Notes
For an inviting presentation, serve topped with Greek yogurt, fresh apple slices, and a drizzle of maple syrup.