Preheat your oven to 350°F and lightly grease a small loaf pan with coconut oil or parchment paper.
In a large mixing bowl, whisk together the Greek yogurt, whole eggs, egg white, pumpkin puree, maple syrup, and vanilla extract until the mixture is completely smooth.
In a separate medium bowl, sift together the whole wheat flour, pumpkin pie spice, ground cinnamon, baking powder, and sea salt.
Gently fold the dry ingredients into the wet yogurt mixture using a spatula, stirring just until no flour streaks remain to keep the bread tender.
Transfer the batter into the prepared loaf pan and use the back of a spoon to smooth the surface evenly.
Bake for 35 to 40 minutes, or until the top is golden brown and a toothpick inserted into the center comes out clean.
Remove the pan from the oven and let the bread cool for at least 15 minutes before slicing into thick, hearty portions.