In a large bowl, mix together the oats, almond milk, mashed bananas, maple syrup, brown sugar, coconut oil, baking powder, cinnamon, vanilla extract, and sea salt using a rubber spatula.
Line a 9x9 pan with parchment paper and pour the oat mixture into it. Sprinkle walnuts and chocolate chips on top.
Bake for 35 to 40 minutes until it's fully set in the center and has crispy edges. Be careful not to overbake.
Once out of the oven, let it cool for 10 minutes, then slice it into individual servings and enjoy it warm!