In a large bowl combine very well mashed bananas, yogurt, eggs, and oil if using. Mix really well.
Add oats, cinnamon, flour, and baking powder. Mix until flour disappears. Do not over mix. Batter will be lumpy.
Heat a small 8-inch pan on medium heat. Note: 8-inch pan usually has only 7-inch cooking surface, so you'll get 7-inch pancakes.
Add coconut oil and melt it to cover the bottom of the pan.
Spread 1/4 of the batter in the pan, add about 3-4 long slices of banana on top and press slightly inside the batter.
Cook on medium or medium-low heat for about 5-6 minutes. Since the pancake is really big, it takes a bit longer to cook.
Once the top of the pancakes stops being glossy and little bubbles start to appear, flip the pancake using a large spatula. Note: you can also slide the pancake off the pan onto a large plate, then place the pan over it and flip the plate and pan together, this way the cooked part of the pancake will be facing up. I tried both spatula and the plate flip method and plate flip was easier.
Cook for another 3-4 minutes until bananas caramelize and the pancake is cooked through.
Wipe the pan with paper towel before cooking another pancake.
Since the pancakes take almost 10 minutes each to make, keep them warm in the oven at 200-225F.