Preheat oven to 350°F (175°C). Spray an 8 x 8-inch baking dish with nonstick spray.
Stir together the oats, baking powder, cinnamon, and salt in a large bowl.
Add the milk, eggs, maple syrup, vanilla extract, apples, and walnuts. Mix well.
Transfer mixture to baking dish, then bake until oats are set and top is lightly browned (about 40 to 45 minutes).
Serve oatmeal hot or warm. Enjoy!
Notes
I used honeycrisp apples to make this, but other crisp varieties, like Braeburn, fuji, pink lady, granny smith, or gala, will also work. Feel free to leave the skins on like I did or peel them off, if you prefer.You can serve Baked Oatmeal on its own, or top it with yogurt, fresh fruit, or nuts. Sprinkle with a little brown sugar or drizzle with maple syrup if you like a sweeter breakfast.Make sure to check out the info before this recipe card for more tips and tricks, serving ideas, and related recipes!