Make the custard: in a large bowl, whisk together the coconut milk, eggs, maple syrup, coconut oil or ghee, banana, vanilla, and sea salt until smooth.
Grease a 9x13 casserole dish with coconut oil or ghee. Roughly tear apart the Little Northern Bakehouse Wide Loaf Bread into 2-inch pieces and arrange in the pan in an even-ish layer (you should have around 4 cups total. Top with the walnuts or pecans, and chocolate.
Pour the custard over the bread, using your hands or a spatula to press down any rogue pieces so they are all more or less submerged. Allow the bread to rest at room temperature for at least an hour so it absorbs the custard, or cover and place in the fridge to sit overnight.
When ready to bake the banana bread pudding, preheat the oven to 400 degrees F.
Transfer the casserole dish to the middle of the oven and bake for about 40 minutes, or until puffed and lightly browned on top.
Remove the banana bread pudding from the oven and allow it to rest in the pan for at least 10 minutes before cutting into it. Then serve topped with vegan vanilla ice cream or crème fraiche, if needed.