Preheat the oven to 375F and grease a square 9x9 baking pan.
Blend:
In a blender, add the milk, banana, melted butter, maple syrup, egg, and vanilla. Blend until the mixture is smooth.
Measure the dry ingredients:
In a large bowl, combine the oats, cocoa powder, baking powder, and salt.
Combine:
Pour the wet ingredients into the dry ingredient bowl, and with a wooden spoon, combine.
Transfer the oat mixture to the prepared baking dish, and distribute the oats evenly in the pan with the spoon. Top with chocolate chips and incorporate them in the batter, leaving a few on top for some chocolatey goodness.
Bake:
Bake for 30 minutes until the oatmeal in the middle has set. Remove from the oven.
Serve & store:
Serve with a drizzle of peanut butter and your favorite toppings.
Leftovers can be refrigerated for up to 4 days. To reheat, microwave each portion in a bowl for 1 minute until warm. This oatmeal does not freeze well.
Notes
Coconut oil or vegan butter makes a good 1:1 substitution for butter
Swap the egg for egg flax by mixing 1 tablespoon ground flax with 3 tablespoons warm water. Wait until a gel-like mixture forms, about 10 minutes.