Preheat the oven to 350 degrees. Use muffin liners or grease the muffin tray.
In a small bowl, combine the flaxseed with 4 tablespoons of warm water. Let sit for 5 minutes.
In a large bowl, the flour, cornstartch, pumpkin pie spice, baking powder, baking soda, and salt.
In another bowl, combine the almond milk, apple cider vinegar, maple syrup, oil, and vanilla and stir to combine. Add the flaxseed mixture.
Add the wet ingredients to the dry and stir until just combined. Add the mashed banana and chocolate chips.
Scoop 1/3 cup of batter into each muffin tray. Cook for 20 minutes or until a toothpick inserted in the center comes out clean. Let the muffins throughly cool before enjoying.