Preheat oven to 375℉. Butter an 8-inch square baking dish.
Core the apples and chop into bite-sized pieces. Place in a large bowl, along with the oats, walnuts, pumpkin seeds, raisins, baking powder, salt, cinnamon, ground ginger, and ground cardamom. Toss to mix.
In a separate bowl whisk together the milk, maple syrup, egg, melted butter, and vanilla.
Add the apple-oat mixture to the prepared baking dish, and then pour the milk mixture over top of the oats. Bake for 35-45 minutes, until the oats are set and the top is golden brown. Serve warm.
