Preheat the oven to 375 degrees. In a large bowl, whisk together the apple sauce, eggs, brown sugar, vanilla, cinnamon, salt, and baking powder until smooth. Add the milk and whisk until smooth again.
Rinse the cranberries in a colander. Slice or roughly chop the cranberries in half (they don't have to be perfect). Stir the cranberries and oats into the applesauce mixture.
Pour the oatmeal mixture into an 8x8 or 9x9 casserole dish (coated with non-stick spray). Bake in the preheated oven for 45 minutes, or until the surface is a light golden brown and it is no longer sticky in the center. Serve hot or refrigerate until ready to eat.