Preheat the oven to 350°F (180°C).
Prepare the flax egg - mix 1 tbalespoon of flax meal and 3 tablespoon lukewarm water in a small bowl. Set aside until gooey.
In a large bowl, whisk all the dry ingredients together: oats, chia seeds, cinnamon, baking powder, salt, and chocolate chips.
In another bowl, whisk all the wet ingredients until well combined: flax egg, peanut butter, maple syrup, vanilla, and milk.
Pour the wet ingredients onto the dry and stir to bring them together.
Pour the baked oatmeal mixture into the prepared baking dish.
Bake the oatmeal on the center rack of the oven at 350°F (180°C) for 35-45 minutes or until set in the center.
Serve with banana slices, extra chocolate chips, and a drizzle of fresh peanut butter.
