Preheat oven to 350 degrees F (176 C) and grease a 2-quart (or similar size) baking dish with oil (or vegan butter), or line with parchment paper.
Prepare flax eggs by combining flaxseed meal and water in a large mixing bowl. Then add ripe banana, maple syrup, oil, salt, and cinnamon and whisk to combine.
Add dairy-free milk and whisk once more. Then add oats, nuts, and half of the chocolate chips and stir to combine.
Transfer mixture to the prepared baking dish and top with additional banana slices, nuts (optional), and remaining chocolate chips. Sprinkle with coconut sugar for a “swirl” effect (optional). You can also drizzle with a little nut butter — such as almond or peanut — for even more flavor (optional).
Bake for 30-35 minutes or until the top is golden brown, the edges are slightly caramelized, and it has some springiness in the center. Remove from oven and let cool a few minutes.
Serve warm with desired toppings, such as warmed coconut milk or almond milk and a drizzle of maple syrup or additional nut butter.
Store leftovers covered in the refrigerator 3-4 days (or in the freezer up to 1 month), though best when fresh. Reheat in a 350-degree F (176 C) oven or in the microwave until hot, adding more dairy-free milk as needed to moisten.
*If subbing eggs for the flax eggs, we'd suggest using 2 eggs in place of the 2 Tbsp (14 g) flaxseed meal and 5 Tbsp (75 ml) water. *This recipe can also be baked in smaller ramekins for ~20-25 minutes. *Nutrition information is a rough estimate calculated with coconut oil, half unsweetened almond milk and half light coconut milk, and walnuts, without optional ingredients.