Preheat oven to 375°F (190°C) and line a 12-cup muffin pan with lightly sprayed liners.
In a small bowl, mix 3 tablespoons chia seeds with 4 tablespoons of water and let sit until gelled (1 minute).
In a large bowl, mash 3 large ripe bananas, then whisk in 1 large egg, ½ cup Greek yogurt, ¼ cup honey, 1½ teaspoons vanilla extract, and the chia gel until smooth.
Stir in 1 cup rolled oats, 1 cup whole wheat flour, 1½ teaspoons cinnamon, 2½ teaspoons baking powder, ½ teaspoon baking soda, and 1 pinch salt until just combined — don’t overmix.
Divide batter evenly into the muffin cups and bake for 20–25 minutes, or until a toothpick comes out mostly dry.
Let muffins sit in the pan for 5 minutes, then transfer to a rack to cool completely.
