Apple Cinnamon Baked Oatmeal (Make-Ahead, Custardy, Full of Apples)

This apple cinnamon baked oatmeal is what my kitchen smells like every Sunday from the first week of October until Thanksgiving: a pan of rolled oats, diced apples, Greek yogurt, maple syrup and a lot of cinnamon that bakes into something between oatmeal and a soft apple cake. It takes 15 minutes to stir together and 35 to bake, it slices into eight neat squares, and every one of them reheats in the microwave in under a minute with a splash of milk — which means breakfast is handled for the week with 12g of protein a square. It started as a fall twist on my banana baked oatmeal, it sits right next to the pumpkin baked oatmeal in the rotation now, and on weekends I serve a warm square beside a plate of cottage cheese scrambled eggs for a breakfast that holds the whole house until lunch.

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Why this apple baked oatmeal is softer and more flavorful than most.

• Greek yogurt in the custard. Most baked oatmeal is oats, milk and an egg, and it can bake up dry and crumbly. A cup of Greek yogurt whisked into the wet ingredients keeps the center moist and custardy, adds a little tang that makes the apples taste more like apples, and pushes the protein to 12g a square without protein powder. It is the same trick I lean on in my Greek yogurt banana bread.
• Apples two ways. Diced apples go into the batter so every bite has soft, sweet pieces, and thin slices fan over the top where they roast and caramelize at the edges. Honeycrisp or Granny Smith both hold their shape; a soft apple like Red Delicious turns to mush, so skip it.
• It is honestly better on day three. The oats keep drinking up the custard as the pan sits in the fridge, so this apple cinnamon baked oatmeal gets more tender and more cinnamon-y as the week goes on. That is the whole reason it is my favorite make-ahead breakfast: it is a recipe that improves on you instead of going stale.

Here's what you'll need.

Thirteen pantry-friendly ingredients: old-fashioned rolled oats, two crisp apples, eggs, milk, plain Greek yogurt, pure maple syrup, cinnamon, a little nutmeg, vanilla, baking powder, salt, chopped walnuts and butter for the dish.

Here's how it all comes together.

STEP 1 — Peel and dice the apples.

Heat the oven to 350°F and butter a 9x9 or 8x11 baking dish. Peel and core the apples. Dice one and a half of them into 1/2-inch pieces for the batter, and slice the remaining half apple thinly for the top. Toss the slices with a pinch of cinnamon so they brown nicely.

STEP 2 — Stir the dry ingredients together.

In a large bowl, stir together the rolled oats, cinnamon, nutmeg, baking powder and salt. Mixing the spices into the oats first keeps the cinnamon from clumping in one corner of the pan once the liquid goes in.

STEP 3 — Whisk the custard.

In a second bowl, whisk the eggs, then whisk in the milk, Greek yogurt, maple syrup and vanilla until smooth. Scrape the bottom of the bowl so no streaks of yogurt are left — they bake into dense spots.

STEP 4 — Combine and fold in the apples.

Pour the wet mixture over the oats and stir until everything is evenly moistened, then fold in the diced apples and about two-thirds of the walnuts. Let the mixture sit for 5 minutes so the oats start absorbing the liquid; it bakes up more evenly that way.

STEP 5 — Spread in the dish and top.

Scrape the mixture into the buttered dish and spread it level. Fan the apple slices over the top, scatter the remaining walnuts, and sprinkle with a little cinnamon and a teaspoon of maple syrup or coarse sugar for a glossy, slightly crisp top.

STEP 6 — Bake until golden and set.

Bake 35 to 40 minutes, until the top is golden, the edges are pulling away a little and the center springs back when you press it. Let it rest 10 minutes before cutting into squares. Serve warm with a drizzle of maple syrup and a splash of milk or a spoon of yogurt.

If a big pan of make-ahead breakfast that quietly carries protein and fiber is your idea of a good Sunday, you will find a dozen more like it in the Ultimate GLP-1 High Protein High Fiber Cookbook.

Things I learned while testing this recipe.

• Old-fashioned oats only. Quick oats go pasty and steel-cut stay crunchy at this bake time. Old-fashioned rolled oats soften just enough while keeping a little chew. Certified gluten-free rolled oats work exactly the same.
• Use crisp, tart-sweet apples. Honeycrisp, Granny Smith, Pink Lady or Braeburn all hold their shape and give the oatmeal real apple flavor. Peeling is optional, but I think the texture is nicer without skins in a soft bake.
• Let the batter rest 5 minutes before baking. Giving the oats a head start on the liquid means the top bakes as moist as the bottom. If you are making it the night before, you can refrigerate the assembled, unbaked pan and bake it straight from the fridge with 5 extra minutes.
• Do not overbake. The center should spring back but still feel soft. It firms more as it cools, and overbaked oatmeal is dry oatmeal. If your oven runs hot, start checking at 32 minutes.

Why this is the fall breakfast I meal prep every week.

• 12g protein and 5g fiber a square, from whole foods. Oats, eggs, Greek yogurt, milk and walnuts do the work — no protein powder. Serve it with a spoon of extra Greek yogurt and you are at 18g, which puts a real dent in your morning protein target.
• One pan, eight breakfasts. Fifteen minutes of stirring on Sunday turns into eight grab-and-reheat breakfasts, each one more filling than a bowl of cereal and sweeter-tasting than the maple syrup count suggests, because the apples bring most of the sweetness.
• Kids eat it like cake. It slices into neat squares, it is soft and cinnamon-y, and it holds together in a lunchbox or a hand on the way out the door. The same goes for the pumpkin protein muffins and blueberry protein muffins I rotate it with.

Here's what I'd serve with this.

• Cottage cheese scrambled eggs — the savory half of my weekend breakfast plate
• High protein overnight oats — the no-bake version for mornings you forgot to turn the oven on
• Cottage cheese egg bites — two bites plus a square is a 30g breakfast
• Greek yogurt bagels — for the family members who want something savory on the side
• Freezer breakfast sandwiches — prep both on Sunday and breakfast is solved for the whole house

Just in case you have leftovers.

Storing: Cool completely, then cover the pan or move the squares to an airtight container and refrigerate for up to 5 days. To freeze, wrap individual squares in parchment and foil or stack them in a freezer bag with parchment between the layers; they keep for 3 months. Thaw overnight in the fridge or reheat straight from frozen.

Reheating: Microwave one square with a splash of milk for 45 to 60 seconds (about 2 minutes from frozen), or rewarm the whole pan, covered with foil, in a 325°F oven for 15 to 20 minutes. The milk soaks in as it heats and brings back that just-baked custardy texture.

More easy breakfast recipes...

Banana baked oatmeal Pumpkin baked oatmeal High protein overnight oats Blueberry cottage cheese breakfast bake

Also new this week: cinnamon apple cake — the dessert version of this flavor, a tender snack cake with a crackly cinnamon sugar top that uses up the rest of the apple bag.

Breakfasts that hold you until lunch

Filling, fiber-rich, make-ahead breakfasts like this baked oatmeal are the backbone of the Ultimate GLP-1 High Protein High Fiber Cookbook — recipes that keep you satisfied on a smaller appetite without ever tasting like diet food.

Get the cookbook on Amazon

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