Healthy Baked Oatmeal: The Easiest Make-Ahead Method

updated Jul 20, 2023
Healthy Baked Oatmeal: The Easiest Make-Ahead Method
Learn how to assemble a baked oatmeal at night for an easy and delicious morning.

Serves4 to 6

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Credit: Joe Lingeman

Whether you bake it in the oven, zap it in the microwave, simmer it on the stovetop, or forget about it overnight in the slow cooker or the fridge, oatmeal is the queen of breakfast foods. Despite the myriad ways oatmeal can be prepared, the holy grail of oatmeal has always been elusive.

I want a hot breakfast in the morning without dirtying the kitchen, and there needs to be enough to serve a crowd or to simply last me through the week. Baked oatmeal is all of these things and, above all, it is supremely flexible; with a few smart swaps it can suit vegan or low-sugar diets. This make-ahead oatmeal recipe can be made in three easy steps.

Make-Ahead Oats for an Easy Monday Morning

Make-ahead breakfasts always seem to come out of the refrigerator (I’m looking at you, chia pudding and overnight oats). Although I love that grab-and-go ease for mornings when I’ve slept through my alarm, a hot breakfast is the one thing I need to truly start the day off right.

But the problem is that I despise making a mess of the kitchen first thing in the morning. This make-ahead baked oatmeal means I can measure and mix the night before so that there are no crumbs to wipe up or pots to clean before heading out for the day.

Credit: Joe Lingeman

For Your Information

  • You’ll need 2 cups of old-fashioned rolled oats for this. Do not substitute instant or quick-cooking oats, as their texture is too fine.
  • One large egg (or 1 tablespoon of flaxseed meal mixed with 3 tablespoons of water, for a vegan option) gives the baked oatmeal a scoopable, custard-like texture.
  • Refrigerate at least 8 hours or overnight before baking.
Credit: Joe Lingeman

Baked Oatmeal for All Diets

Baked oatmeal can easily be adapted to suit all types of diets without sacrificing texture or flavor. If you want to make baked oatmeal for a vegan crowd, simply substitute coconut oil for the butter, flaxseed meal for the egg, and your favorite non-dairy milk for cow’s milk.

For those looking to reduce their sugar intake, simply omit the sweetener. The inclusion of vanilla extract and cinnamon give the illusion of sweetness without the additional sugar.

Are you gluten-free? This baked oatmeal is for you too! Just check the labels (as I’m sure you always do) to make sure you choose oats and flaxseed meal that have not been processed on shared machinery.

Healthy, You Say?

Oatmeal is the perfect breakfast food because it will stay with you long past your morning commute. This is all thanks to soluble fiber, specifically beta-glucan. Once ingested, soluble fiber turns to a gel, slowing digestion, keeping you feeling full longer.

One of the more well-known health benefits is that it lowers LDL (“bad”) cholesterol. Thanks again to beta-glucan, oatmeal has been linked to a decreased risk of heart disease, with strong enough scientific evidence that oat manufacturers are allowed to put a health claim on their packages.

Credit: Joe Lingeman

3 Easy Steps for Make-Ahead Baked Oatmeal

  • Stir all ingredients together. Whisk all of the ingredients, except the oatmeal, together first to evenly distribute. Stir in the oatmeal.
  • Pour oatmeal into an 8×8-inch baking dish and refrigerate overnight. Transfer the oatmeal mixture to a greased baking dish, cover, and refrigerate until morning.
  • Bake the oatmeal for 45 minutes. In the time it takes to get ready for work, you can pull a batch of piping-hot oatmeal out of the oven without creating a pile of dirty dishes in the sink.

Old-Fashioned Oats Are the Right Choice for Baking

All oats start life as oat groats. To make old-fashioned rolled oats, oat groats are steamed and rolled flat into discs. Old-fashioned rolled oats are the right choice for baking because they cook up creamy, but still retain their shape and chew.

Serving and Storing Baked Oatmeal

Scoop creamy baked oatmeal into bowls and top with seasonal fruit and a little something sweet. In the fall, add chopped apples and an extra drizzle of maple syrup. In the summer, make the vegan version and top it with toasted coconut and fresh berries from the farmers market.

Leftovers keep for several days in the refrigerator. Simply microwave a serving with a splash of milk to loosen it up. Whether we start winter mornings in the dark or wake up with the sun in the summer, baked oatmeal is an easy and healthful and satisfying way to start the day and keep you running until lunch.

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Healthy Baked Oatmeal: The Easiest Make-Ahead Method (Image credit: Joe Lingeman)

Healthy Baked Oatmeal: The Easiest Make-Ahead Method

Learn how to assemble a baked oatmeal at night for an easy and delicious morning.

Serves 4 to 6

Nutritional Info


  • 2 tablespoons unsalted butter, or melted and cooled coconut oil, plus more for the baking dish
  • 1 large egg, or 1 tablespoon flaxseed meal whisked with 3 tablespoons water
  • 3 cups dairy or non-dairy milk
  • 1/4 cup sweetener, such as maple syrup, brown sugar, or coconut sugar
  • 2 teaspoons vanilla extract
  • 1 teaspoon ground cinnamon
  • 1 teaspoon baking powder
  • 1/4 teaspoon salt
  • 2 cups old-fashioned rolled oats

Optional mix-ins and toppings:

  • chopped nuts, fresh, frozen or dried fruit, chocolate chips, toasted coconut


  • Measuring cups and spoons
  • Mixing bowls
  • Whisk
  • Spatula or wooden spoon
  • 8x8-inch baking dish
  • Plastic wrap


  1. Grease an 8x8-inch baking dish. Lightly coat an 8x8-inch baking dish with melted butter or coconut oil; set aside.

  2. Assemble the oatmeal. Whisk the butter or coconut oil, egg or flax-water mixture, milk, sweetener, vanilla, cinnamon, baking powder, and salt together in a large bowl. Stir in oats and any fruit or nut mix-ins.

  3. Refrigerate the oatmeal overnight. Pour the oatmeal mixture into the prepared baking dish. Cover with plastic wrap and refrigerate 8 hours or overnight.

  4. Heat the oven and stir the oatmeal. Arrange a rack in the middle of the oven and heat to 350°F. Remove the oatmeal from the refrigerator while the oven heats. Uncover and stir to redistribute the oats and milk.

  5. Bake the oatmeal for 45 minutes. Bake, uncovered, until puffed and the center is just set, about 45 minutes. Nuts can be sprinkled on top during the last 5 minutes of baking. Serve warm with desired toppings.

Recipe Notes

Storage: Refrigerate leftovers for up to 4 days. Reheat single servings in the the microwave with a little bit of milk.