Preheat Oven: Heat oven to 350°F (180°C).
Prep Oats: Add half of the oats into a blender and blend into dust.
½ cup rolled oats
Mix Dry Ingredients: In a medium bowl, mix rolled oats, salt, baking powder, cocoa powder, cinnamon, and brown sugar.
⅛ tsp salt, ¼ tsp baking powder, ½ tbsp cocoa powder, ¼ tsp cinnamon, 1 tsp brown sugar
Mix Wet Ingredients: Add milk, Greek yogurt, mashed banana, and vanilla extract (if using); stir to a smooth batter.
¼ cup milk, 2 tbsp Greek yogurt, ½ large ripe banana, ¼ tsp vanilla extract
Prepare Baking Dish: Lightly grease baking dish with butter, oil, or non-stick spray.
Fill: Pour batter evenly into the greased dish.
Bake: Bake for about 25 minutes, until top is firm and a toothpick inserted comes out mostly clean.
Cool: Turn off oven, crack door open, and let oats cool inside for 5 minutes.
Serve: Serve warm or chill before enjoying.