To a bowl, mix together the milk, eggs, vanilla, cinnamon and salt.
Place the bread pieces, diced apples, raisins, pecans, flax and hemp hearts into the baking dish and pour the egg mixture on top. Toss everything together to coat in the liquid, then cover with plastic wrap and let it sit in the fridge overnight.
When ready to eat, preheat oven to 350 F.
Mix together the melted butter and maple syrup and pour over the casserole. Bake for 45-55 minutes, or until golden brown on top. Allow to sit for at least five minutes.
Serve with yogurt, fruit, berry sauce, or more maple syrup.