Preheat oven to 375 degrees Fahrenheit.
Peel and dice 1/2 of a large, crisp apple.
To the baking dish, add the oats, diced apple, cranberries, walnuts, and collagen powder (optional). Stir the ingredients together well.
Add the almond milk, vanilla, and cinnamon. Stir everything together well.
At this time, assess if you want to add any more of the apple, cranberries, or walnuts to suit your taste.
Bake uncovered at 375 degrees for 45 minutes until the top of the baked oatmeal is lightly browned and the almond milk is mostly cooked into the oats.
Let rest for 5-10 minutes before serving. If desired, top each serving with your favorite sweetener such as maple syrup, honey, or brown sugar.
