1. Prepare your oven and loaf pan: Preheat your oven to 350 F (175 C). Lightly grease and flour a 9×5-inch loaf pan, or line it with parchment paper for easy removal. This prevents sticking and ensures a beautiful loaf.

2. Mash the bananas: In a large mixing bowl, thoroughly mash the ripe bananas with a fork until mostly smooth but with a few small lumps remaining. These lumps add nice texture to the finished bread.

3. Combine wet ingredients: To the mashed bananas, add the eggs, applesauce (or Greek yogurt), maple syrup (or honey), and vanilla extract. Whisk everything together until well combined and smooth.

4. Mix dry ingredients separately: In a separate medium bowl, whisk together the whole wheat flour, protein powder, baking soda, ground cinnamon, and salt. Make sure there are no lumps in the dry mixture.

5. Combine wet and dry mixtures: Gradually add the dry ingredients to the wet ingredients, mixing with a spatula or wooden spoon until just combined. Be careful not to overmix, as this can lead to a tough bread. A few streaks of flour are perfectly fine. If using, gently fold in any optional additions like walnuts or chocolate chips now.

6. Transfer to the loaf pan: Pour the batter evenly into your prepared loaf pan. You can gently tap the pan on the counter a few times to settle the batter and remove any large air bubbles.

7. Bake until golden: Bake for 45-55 minutes, or until a wooden skewer or toothpick inserted into the center of the loaf comes out clean. The top should be golden brown and the edges slightly pulled away from the pan.

8. Cool before slicing: Let the banana bread cool in the pan for about 10-15 minutes before carefully removing it and transferring it to a wire rack to cool completely. Slicing while warm can make it crumbly.