In a large bowl, whisk together the flours, oats, chia seeds, sugar, baking powder, baking soda, and salt. In a medium bowl, whisk together the mashed banana and eggs. Then whisk in the yogurt and milk. Using a spatula, add the wet ingredients to the dry ingredients, stirring and folding to combine. Stir in the melted butter. Don't overwork the batter here. It should be a bit lumpy with no large pockets of dry ingredients.
Preheat a cast-iron skillet over medium-high heat or an electric griddle to 375°F. Brush the skillet lightly with melted butter. Using a ladle, pour pools of batter on the hot skillet. I can get 3 pancakes on a 12-inch skillet or 6 on a rectangular electric skillet. Adjust the size of your pancakes based on taste (I like mine not too small, but not too big). When the pancakes have bubbles on top and are slightly dry around the edges, about 2 minutes, flip over. Cook on the other side for an additional minute, until golden. Repeat with the remaining batter. You can keep the finished pancakes on a baking sheet in the oven at 175°F covered with a clean kitchen towel.
To serve, top each stack of pancakes with sliced bananas, fresh berries and drizzle with maple syrup. Enjoy warm!