1. Preheat the oven to 350 F and grease a 9″ pie plate or 8×8″ baking dish. In a large mixing bowl, whisk together the oats, baking powder, nutmeg, cinnamon, and salt. In another microwave-safe bowl, heat the coconut oil until melted. Add the honey, egg and vanilla extract and whisk thoroughly. Whisk in the milk.
2. Pour the wet ingredients into the dry, along with the shredded carrots and chopped nuts. Stir to combine, then empty everything into the greased baking dish. Use a spoon to gently press it all down. Bake the oatmeal for 25-30 minutes, or until the middle of the oatmeal no longer jiggles when you give it a light shake. Remove and let stand for 5 minutes.
3. Prepare the cream cheese frosting: In a stand mixer fitted with the paddle attachment, or using a handheld electric mixer, beat the softened cream cheese for 1 minute on high, until smooth. Add the powdered sugar and the cream and mix again until smooth. Add either more powdered sugar, or more cream to get the desired consistency.
4. Drizzle the frosting all over the oatmeal and serve immediately.

Leftover oatmeal can be stored in an airtight container, in the fridge, for 4-5 days. Reheat portions of the oatmeal in the microwave.