Preheat the oven to 350°F. Mist a 9×9 baking dish with cooking spray; set aside.
To a mixing bowl, add the oats, chia seeds, baking powder, salt, cinnamon, ginger, and nutmeg. Stir to combine.
Add the maple syrup, eggs, milk, vanilla, and melted butter. Stir well to combine.
Fold in the shredded carrots, raisins, and walnuts.
Pour batter into the baking dish, smoothing the top. Top with additional chopped walnuts, if desired. Bake for 30-35 minutes or until the center is set and a toothpick inserted in the center comes out clean.
While the oatmeal is baking, mix together the icing. In a small bowl, combine the whipped cream cheese, milk, maple syrup, and vanilla until smooth. Add additional milk, 1 teaspoon at a time, until icing is a drizzly consistency.
Remove the baked oatmeal from the oven and let cool for 15 minutes before drizzling with icing and cutting into squares.
Store any leftovers in an airtight container in the fridge for up to 2 days.
