Preheat your oven to 350ºF and line a muffin tin with 12 paper liners. These muffins tend to stick to the muffin liners because there's no oil in the batter, so I don't recommend simply greasing the pan.
In a large mixing bowl, mash the 3 bananas with a fork until they look like puree. Then add in the peanut butter, eggs, protein powder, honey, baking powder, vanilla, and salt. Stir well, breaking up any lumps you see in the batter. (Using a whisk helps with this, even though the batter is thick!)
Fold in the chocolate chips, if using, then divide the batter among the 12 muffin cups. This batter should fill the muffin cups up nearly to the top. Bake at 350ºF for 25 minutes or until the tops of the muffins feel firm to the touch.
Let the muffins cool in the pan for 30 minutes. Then they are ready to enjoy. Because these muffins are so moist, I recommend storing leftovers in an airtight container in the fridge for up to 5 days. Or you can freeze them for up to 3 months.
Notes
Nutrition information is for 1 of 12 muffins without the optional chocolate chips. This information is automatically calculated using generic ingredients from a database, so it's just an estimate and not a guarantee.Peanut Butter Note: I tested this recipe with salted peanut butter. (The all-natural kind that needs to be stirred when opened.) If you use unsalted peanut butter, you might want to add an extra pinch of salt to the batter. I'm not sure how processed peanut butter, like Jiff or Skippy, would work in a recipe like this one, so experiment at your own risk.Protein Powder Note: I tested this recipe with Garden of Life Unsweetened Plant Based Protein powder. It does not taste good on its own, but you don't notice it in these muffins. Feel free to experiment with other brands and flavors.High-Protein Note: Recipes that are 20% protein or higher on my website fall into the high-protein category. You can calculate this by multiplying the grams of protein by 4 and dividing that answer by the total number of calories per serving. (In this case, it's 9 x 4 = 36; 36 ÷ 180 = .20 or 20%.)