In a large bowl, whisk together 1 cup whole wheat flour, 3/4 cup all-purpose flour, 1/4 cup rolled oats, 2 tablespoons chia seeds, 2 tablespoons sugar, 2 teaspoons baking powder, 1/2 teaspoon baking soda, and 1/2 teaspoon fine-grain salt until evenly combined.

In a medium bowl, whisk the 1/2 cup mashed ripe banana with 2 eggs until blended.

Whisk the 1 cup plain whole milk yogurt, 3/4 cup whole milk, and 1 teaspoon vanilla into the banana–egg mixture until smooth.

Add the wet mixture to the dry ingredients. Using a spatula, stir and fold just until the batter is combined; it should be a bit lumpy with no large pockets of dry flour. Do not overwork the batter.

Stir in the 3 tablespoons melted and cooled unsalted butter until incorporated. If you have any melted butter left over, reserve a small amount for the pan.

Preheat a cast-iron skillet over medium-high heat or an electric griddle to 375°F. If any melted butter remains, lightly brush the skillet with it.

Using a ladle or a 1/4-cup measure, pour portions of batter onto the hot skillet to form pancakes of your desired size. Leave space between pancakes.

Cook until bubbles appear on the surface and the edges look set and slightly dry, about 2 minutes. Flip and cook the other side until golden, about 1 minute more. Adjust heat as needed to prevent burning.

Repeat with the remaining batter. Keep finished pancakes warm on a baking sheet in a 175°F oven, covered with a clean kitchen towel, if desired. Serve warm.