Mash the banana inside a zip bag or in a large bowl until it resembles a thick paste with minimal clumps. Add an egg to the bowl, and whisk it well while combining it with the banana. Then, add the peanut butter and mix it well. Add the milk and mix until smooth. Mixing the peanut butter and banana with the liquid ingredients prevents overmixing the batter, which leads to chewy pancakes.
In a medium bowl, whisk the dry ingredients. Then, add the mix to the large bowl with the wet ingredients and gently mix, from the outside of the bowl in, until the flour is incorporated and no visible flour is left. Some clumps are ok.
Cook the pancakes:
Heat a non-stick pan or griddle over medium heat. Once hot, grease it. Immediately pour ¼ cup of batter per pancake. Use the back of a spoon or the scoop to spread and shape the pancakes into circles. The batter is thick and won't spread.
Cook the first side for about 2 minutes, until the edges begin to look defined and bubbles form. Flip the pancakes over and cook the second side for a little less time. Remove them onto a plate, cover them to keep them warm or serve as you go.
Serve and store:
Serve them warm, topped with your favorite toppings and syrups.
Refrigerate leftovers in an airtight container for up to 3 days or freeze for up to 3 months. Reheat in the microwave for 30 seconds to 1 minute, or in a toaster.