1. Preheat the oven to 350°F (175°C). Lightly grease a 9-inch (23cm) square pan with oil.
2. In a bowl, stir oats, flour, baking powder, baking soda, cinnamon, nutmeg and salt. Set aside.
3. In a separate bowl, whisk egg whites, vanilla extract and coconut oil. Add yogurt, maple syrup and milk. Whisk until combined.
4. Add oat mixture to the wet mixture, stir until combined. Add diced apples and stir.
5. Pour the batter into prepared pan. Bake for 25-30 minutes or until lightly golden and toothpick inserted into the center comes out clean.
6. Let cool before slicing. Cut into squares or bars.
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