Place the bananas, soy milk, apple cider vinegar, and ground flax, in a food processor. Pulse until smooth. Add the sliced butter, vanilla, and agave nectar and pulse again until combined. Set aside.
Stir together the oat flour, gluten-free flour, baking powder, and cinnamon in a large bowl.
Pour the banana mixture into the flour mixture and stir until just combined. See note for batter consistency tips. Let the batter sit for 10 minutes.
Once the batter is ready, place a skillet over medium heat and give it a light coating of vegetable spray or oil. Or heat a non-stick griddle to 375°F/190°C. Even a non-stick surface can add flavor to cooking pancakes by adding a little vegan butter to the surface.
Pour batter in the shape of a circle in the prepared skillet or griddle. Repeat with the available space in your skillet, allowing about an inch between each pancake. Cook for 3 to 5 minutes, until the bottom of the pancakes, are golden brown. Use a spatula to pull up a corner of one of the pancakes to make sure they're cooked to a golden color on the bottom. Flip the pancakes and cook on the other side for an additional 3 to 5 minutes until the pancake is golden-colored on both sides.
Place cooked pancakes a single layer on a pan and place them either in a warmed toaster oven or oven set to 200°F/90°C to stay warm while you prepare the rest of the pancakes.
Serve with vegan butter, peanut butter, maple syrup, and/or sliced bananas.