Apple Cinnamon Baked Oatmeal (One Bowl, No Mixer)

Baked oatmeal gets treated like a novelty — a thing you make once for brunch and never again. That’s a mistake. This version is closer to a breakfast casserole than a “treat.” It holds up in the fridge for days, it reheats without turning to mush, and it’s got enough protein and fat in it from the eggs and butter that it actually keeps you full past 10am.

Why This Works

Most baked oatmeal recipes go soggy in the middle because people either use quick oats (too fine, they dissolve) or they skimp on binding. This recipe uses old-fashioned rolled oats specifically — they hold their shape and give you texture instead of paste.

The applesauce does double duty. It’s moisture, but it’s also sugar and pectin, which helps the whole thing bind without needing a ton of extra egg or flour. Skip it and swap in more milk instead, and you’ll get a looser, wetter bake — not wrong, just different, and not what this recipe is testing for.

Folding the shredded apple in at the end instead of at the start matters too. Stir it in with everything else from the beginning and it releases water into the batter before it ever hits the oven, which is part of why some versions of this dish turn gummy in the center.

Ingredients

• 2 ¾ cups old fashioned rolled oats (285 g)
• 1 tablespoon chia seeds, optional (10 g)
• 1 ½ teaspoons ground cinnamon
• 1 teaspoon baking powder
• ¼ teaspoon fine salt
• ¼ cup maple syrup or honey (70 g)
• ½ cup unsweetened applesauce (115 g)
• 2 large eggs (110 g)
• 1 ¼ cups milk of choice (300 g)
• ¼ cup melted unsalted butter or coconut oil (60 g)
• 1 teaspoon pure vanilla extract
• 1 cup shredded apple or finely diced, plus more for topping (115 g)
• ⅓ cup chopped walnuts, toasted (35 g)

Instructions

1. Preheat the oven to 375°F.
2. Spray a 9×9 or 8×8-inch baking dish with cooking spray.
3. In a bowl, combine the rolled oats, cinnamon, chia seeds, baking powder, salt, maple syrup, applesauce, eggs, milk, butter, and vanilla. Stir until combined.
4. Fold in the shredded apple and toasted walnuts.
5. Transfer the batter to the prepared baking dish.
6. Top with a few extra chopped toasted walnuts.
7. Bake for 30–35 minutes, or until the center is set.
8. Let sit for 10 minutes before serving — don’t skip this, it’s still finishing up out of the oven.
9. Top servings with whipped topping or yogurt and maple syrup, if you want.

Prep time: 15 minutes Cook time: 30 minutes Total time: 45 minutes Servings: 9

Tips

• Toast the walnuts before folding them in. Raw walnuts in a bake like this go soft and kind of flat-tasting; toasted, they stay crunchy even after a day in the fridge.
• Check the center at 30 minutes, not 35.
• Shred the apple instead of dicing it if you want the pieces to basically melt into the batter. Dice it if you want to actually bite into apple. Both work, they’re just different textures.
• Don’t skip the 10-minute rest. The center is technically cooked at the 30–35 minute mark but it’s not set yet — it firms up as it cools.

Variations

Swap the walnuts for pecans if that’s what you’ve got — no real difference in the outcome. Honey instead of maple syrup works fine too, just slightly less “fall” flavor-wise.

What I wouldn’t do again: subbing the eggs out entirely for a flax egg. It bakes up noticeably wetter in the center and takes longer to set, and at that point you’re better off just calling it something else.

Make-Ahead

This keeps in the fridge, covered, for about 4-5 days. It does not freeze particularly well — the texture goes grainy once thawed, especially around the apple pieces. If you want to meal-prep this, portion it into the fridge, not the freezer.

FAQ

Can I use quick oats instead of old-fashioned rolled oats? No — quick oats break down too much in this recipe and you’ll end up with something closer to a pudding than a baked oatmeal. Stick with old-fashioned rolled.

Do I have to toast the walnuts first? You don’t have to, but you should. Untoasted walnuts baked into a wet batter like this lose their crunch almost entirely, which is most of what they’re there for.

Can I make this dairy-free? Yes, swap in a non-dairy milk and use coconut oil instead of butter. The texture holds up fine either way.

Is this recipe gluten-free? Rolled oats are naturally gluten-free, but check the label if cross-contamination is a concern for you — buy oats certified gluten-free if that matters.

Why did my baked oatmeal turn out soggy in the middle? Almost always one of two things: quick oats instead of rolled, or pulling it out before the center actually set. Give it the full 30-35 minutes and the rest period after.

Closing Thoughts

This one’s good straight out of the fridge, cold, eaten standing at the counter — which honestly might be my favorite way to eat it.

Author Bio

I’m Kima, and I test every recipe on this site in my own kitchen before it goes up — usually more than once. Baked oatmeal specifically has been a years-long project of figuring out how to make it taste like more than “healthy” oats.