Preheat oven to 350°F (175°C) and line a 9x5 inch loaf pan with parchment paper.
In a large mixing bowl, whisk together pumpkin puree, egg whites, and applesauce until smooth.
In a separate bowl, sift together oat flour, protein powder, erythritol, pumpkin pie spice, baking powder, baking soda, and salt.
Gradually fold the dry ingredients into the wet ingredients until just combined; do not overmix.
Pour the batter into the prepared loaf pan and smooth the top.
Bake for 45 to 55 minutes, or until a toothpick inserted into the center comes out clean.
Remove from oven and allow the bread to cool completely in the pan before slicing.