Preheat your oven to 350°F. Grease a 9x13-inch baking dish.
In a large bowl, combine the rolled oats, almond milk, diced apples, brown sugar, applesauce, cinnamon, nutmeg, salt, and vanilla extract. Mix well until all ingredients are evenly combined.
If using, fold in the chopped nuts and dried fruit.
Pour the oatmeal mixture into the prepared baking dish, spreading it evenly.
Bake in the preheated oven for 30-35 minutes, or until the top is golden brown and the oatmeal is set.
Remove from the oven and let it cool for a few minutes before serving. Cut into squares and enjoy warm.