Preheat your oven to 350°F (175°C) and lightly grease a 9x9-inch baking dish.
In a large mixing bowl, combine the rolled oats, almond milk, diced apple, brown sugar, maple syrup, cinnamon, salt, vanilla extract, baking powder, and eggs. Mix well until all ingredients are evenly incorporated.
If using, fold in the chopped nuts and dried fruit.
Pour the mixture into the prepared baking dish and spread it evenly.
Bake in the preheated oven for 30-35 minutes, or until the top is golden brown and the oatmeal is set.
Allow to cool for about 10 minutes before slicing into squares and serving.