Preheat oven to 375 degrees Fahrenheit (190 degrees Celsius) and grease an 8x8-inch baking dish.
In a large mixing bowl, combine the rolled oats, baking powder, cinnamon, ginger, nutmeg, and salt.
Fold in the grated carrots, chopped walnuts, and raisins until evenly distributed.
In a separate medium bowl, whisk together the almond milk, maple syrup, egg, vanilla extract, and melted coconut oil.
Pour the wet mixture over the dry oat mixture and stir until fully combined.
Transfer the mixture to the prepared baking dish, smoothing the top with a spatula.
Bake for 35 minutes, or until the top is golden brown and the oatmeal is set in the center.
Remove from the oven and allow to cool for 5 to 10 minutes before slicing and serving.