Preheat oven to 425F. Mash two large or three medium bananas with a fork or potato mashed until broken down to a chunky applesauce texture. Measure out 1 cup of mashed banana.
Make a flaxseed "egg" by combining 1 tablespoon ground flaxseed with 3 tablespoons water in a small bowl. Let rest for 5 minutes before using.
Combine all dry ingredients in a large mixing bowl: all purpose flour, sugar, brown sugar, baking powder, baking soda, salt, cinnamon, nutmeg. Stir to combine.
Add wet ingredients to dry ingredients: mashed banana, flax egg, soy milk, oil or melted butter, vanilla extract. Stir until there are no more dry spots. Don't overmix. It is okay if some small lumps remain.
Fold in the chocolate chips and pecans.
Line a 12 cup muffin tin with liners or lightly spray with cooking oil (I usually just spray instead of using liners). Add ¼ cup batter to each cup, evening out as needed.
Bake on the middle oven rack at 425F for just 5 minutes. After 5 minutes, turn the heat down to 350F and continue baking for 13-15 minutes, or until the muffins are domed, golden, and pulling away from the pan.
Remove from oven and let rest in muffin tin for 5 minutes before turning out on a wire rack to cool.
Video
Notes
Bananas: Use very ripe bananas. The banana skin should be turning brown or at least heavily speckled (see reference image in post).
Flour: These muffins can be made with half whole wheat in place of white wheat. It will yield a slightly denser muffin. Use the spoon and level method to measure flour. Take a spoon and scoop flour into the measuring cup until overflowing. Use the back of a knife to wipe excess flour off the top. Do not pack flour into cup.
Sugar: I don't recommend replacing sugar with maple syrup or any other liquid sweetener. You can use all granulated sugar or brown sugar, if desired.
I recommend using an oven thermometer. Oven temperatures can vary widely and the only way to know if your oven is the temperature it says it is is to use an oven thermometer.
Add-ins: Fold in up to 1 cup of chocolate chips, chopped nuts, or your other favorite add-in to the batter.