Preheat your oven to 375°F (190°C).
Grease an 8x8 inch baking dish or a similar sized 2 quart dish.
In a large bowl, whisk together the oats, baking powder, salt, and 1 1/2 teaspoons of cinnamon.
In a separate bowl, whisk the milk, egg, melted butter or coconut oil, vanilla extract, maple syrup, and 1/4 cup of brown sugar until smooth.
Pour the wet ingredients into the dry ingredients and stir until everything is combined. Do not overmix. Let it sit for 5 minutes so the oats can start absorbing the liquid.
Pour the oat mixture into the prepared dish and spread it evenly.
In a small bowl, mix together the 2 tablespoons of softened butter, 2 tablespoons of brown sugar, and 1/2 teaspoon of cinnamon to make a paste.
Drop small spoonfuls of this paste over the top of the oatmeal. Use a knife to gently swirl it into the batter. Do not mix it in completely; leave visible ribbons of the cinnamon butter.
Bake for 25 to 30 minutes, or until the top is golden brown and the center is set but still slightly jiggly.
Let it cool for 5 minutes.
While the oatmeal bakes, make the cream cheese drizzle. Beat the softened cream cheese with a fork until smooth. Add the powdered sugar and 2 tablespoons of milk.
Stir until smooth. If it is too thick, add another tablespoon of milk. You want a pourable consistency.
Drizzle the cream cheese mixture over the warm oatmeal.
Serve immediately.