Preheat your oven to 350°F and line a small loaf pan with parchment paper to prevent sticking.
Core and finely dice the apple into small, uniform pieces.
In a medium mixing bowl, whisk together the rolled oats, almond flour, vanilla protein powder, cinnamon, nutmeg, and sea salt.
In a separate small bowl, stir together the almond butter, maple syrup, egg whites, and vanilla extract until the mixture is smooth and well combined.
Pour the wet ingredients into the dry oat mixture and stir until a thick, sticky dough forms.
Gently fold three-quarters of the diced apples into the dough.
Press the mixture firmly and evenly into the prepared loaf pan, then scatter the remaining apple pieces over the top, pressing them slightly into the surface.
Bake for 22 to 25 minutes until the edges are golden brown and the center feels firm to the touch.
Allow the bars to cool completely in the pan before lifting them out and slicing into squares.