Preheat the oven to 375 °F. Lightly spray a 9x13-inch baking dish with nonstick.
Whisk together the applesauce and brown sugar
Whisk in the egg and egg whites, making sure the egg is well-beaten and fully incorporated.
Whisk in the cinnamon, baking powder, salt, vanilla extract
Stir in the coffee and the milk
Stir in the oats
Pour the batter into the prepared baking dish and bake for about 45 minutes, until the edges are lightly brown and a toothpick or knife inserted into the center of the oatmeal comes out clean.
Stir together 1 tablespoon of sugar + ¼ teaspoon cinnamon and sprinkle over the top.