Mixed Berry Oatmeal Bake

This mixed berry oatmeal bake is as delicious as it is gorgeous. All of the sweet-and-tangy goodness of a fluffy berry muffin, baked into a comforting oatmeal breakfast casserole! Learn how to make baked oatmeal with blueberries, strawberries, raspberries, & blackberries—using fresh or frozen berries.

Explore more of the Best Baked Oatmeal Recipes or try my Frozen Baked Oatmeal Cups!

Baked Berry Oatmeal Benefits

Much like stovetop oatmeal, baked oatmeal with berries is a convenient healthy breakfast option. Rolled oats are rich in fiber, complex carbs, and essential vitamins and minerals, while berries offer loads of antioxidants. Baking oatmeal also has benefits in terms of taste, producing a heartier, more satisfying texture that’s more like a muffin than a porridge. Plus, this is an easy, low-stress breakfast that you can make ahead of time! Our health is impacted by much more than just what we eat—including enjoying what we eat and reducing our stress around food.

Healthy Berry Oatmeal Bake Ingredients

• Rolled Oats. You can’t substitute with quick-cooking or steel cut oats here: quick oats will turn to mush in the oven, and steel cut require longer to cook through. It’s best to make this mixed berry baked oatmeal with old-fashioned rolled oats.
• Baking Powder. A must-use ingredient to give your casserole a fluffy, baked-good texture!
• Spices. I stick with simple cinnamon and a bit of salt, but feel free to get creative here.
• Eggs or Flax Eggs. This berry oatmeal bake requires eggs to bind the batter together and produce its bready texture. For a vegan alternative, you can use flax eggs instead, or even fruit puree like mashed banana or applesauce.
• Milk of Choice. Any milk you prefer can work in this recipe—dairy or non-dairy varieties.
• Sweetener. I prefer to use a sticky sweetener like honey or maple syrup, but granulated sweeteners like coconut, brown, or white sugar can all work as well.
• Coconut Oil. The saturated fats in coconut oil add rich, luscious comfort to this baked berry oatmeal casserole, or feel free to use butter for a more flavorful option! If desired, you can omit the oil/butter altogether—your baked oats will just be a bit less light-and-fluffy.
• Vanilla Extract. Add a dash to help all of these sweet flavors shine.
• Mixed Berries. I used fresh blueberries, strawberries, raspberries, and blackberries, or you can make this baked oatmeal with frozen berries for convenience. Feel free to simplify and use just 1-2 types of berries in your casserole—or use different fruits altogether, like in my apple cinnamon baked oatmeal!

Substitutions for a Vegan Berry Oatmeal Bake

You can make this baked berry oatmeal vegan by making it with no eggs! Just replace the 2 eggs with 2 flax eggs (2 Tbsp ground flax + 5 Tbsp water), or substitute with ½ cup mashed banana, applesauce, or pumpkin puree. For a completely vegan oatmeal bake, be sure to use maple syrup instead of honey, and coconut oil rather than butter.

For a Classic Blueberry Baked Oatmeal

Much like the beloved blueberry muffin, a blueberry oatmeal bake is one of the most popular flavors people look for. If you’d like, you can simplify this recipe and make your baked oatmeal with blueberries only—fresh or frozen—instead of mixed berries.

How to Make Baked Berry Oatmeal

1. Choose your baking dish. I designed this mixed berry oatmeal bake recipe for an 8-inch round baking dish or a 9×9-inch square dish, yielding 5-6 servings. For a larger 9×13 casserole that yields 10-12 servings, simply double the ingredient amounts in this recipe and bake for 10-15 additional minutes.
2. Prep the oatmeal casserole batter, then bake. It’s best to combine the dry and wet ingredients only when you’re ready to bake—don’t let the unbaked casserole sit overnight.
3. Bake berry oatmeal at 350°F (180°C) for 40-50 minutes, until browned and crisped on top. You’ll know it’s done when a knife comes out mostly clean.
4. Store oatmeal bake in the fridge for 4-7 days or freeze for up to 3 months. You can either cover and store the entire casserole, or slice it into individual portions and store those in airtight containers or plastic wrap.
5. Reheat baked oats in the oven or microwave until warmed through. An entire casserole can be reheated in the oven at 350°F for 15-20 minutes (or longer if frozen). Individual portions are easy to reheat in the microwave for ~60-90 seconds, or in the oven or toaster oven for 5-10 minutes.

Watch how to make mixed berry baked oats in my 7 Oatmeal Bake Recipes video!

Why are my berry baked oats mushy?

Baked oats may turn out mushy or soggy for several reasons. (1) Using quick-cooking oats instead of rolled oats. (2) It needs to bake longer to fully cook through. (3) The oats sat in the liquid for too long before baking. This is why I don’t recommend letting the unbaked casserole sit overnight—the oats end up soaking up too much liquid, making the texture overly thick and mushy.

How do I meal prep baked berry oatmeal?

Rather than prepping an unbaked casserole and waiting until later to bake it, the best way to meal prep this berry oatmeal bake is to just cook the whole casserole, then store as desired. Store in the fridge if you’re meal prepping for the week, or freeze for longer-term storage. This way, you’ll have easy, ready-to-reheat breakfasts on hand whenever you want them!