Heat oven to 350 and grease a 8x8 baking pan. (I used a glass pan.)
While the oven is heating mix the flax seed meal with 3 tablespoons of water. Let the mixture rest for 5 minutes.
After the flax mixture has rested, whisk in the oat milk, cinnamon, vanilla, maple syrup, salt, and mashed banana until well combined. Taste, and adjust the ingredient amounts, adding more maple syrup or salt, if you like.
Fold in the oats, raisins, and nuts.
Pour the mixture into the greased baking pan, sprinkling with coconut sugar if you wish.
Bake for 50 minutes, or until all the liquid is absorbed and the oats are lightly browned.
Let the baked oats rest for 5 minutes before serving.
Top with more maple syrup, nut butter, and fruit, if you like.