# Baked Oatmeal Casserole > A cozy, make-ahead baked oatmeal casserole that's hearty, wholesome, and perfect for busy mornings. Loaded with whole rolled oats, mashed banana, and juicy blueberries, it bakes into a tender, sliceable breakfast that reheats beautifully for the week. Canonical URL: https://www.topshelf.recipes/recipes/baked-oatmeal-casserole ## Author Jake Woods https://www.topshelf.recipes/chef/jake-woods Published: June 22, 2026 Last Updated: September 3, 2026 ## About This Recipe Baked Oatmeal Casserole is the kind of breakfast that blurs the line between comfort food and sensible meal planning: spoonable warmth that also holds its shape for easy slices, reheating and packing. In this version, mashed banana supplies body, sweetness and a custardy crumb while rolled oats create a toothsome bite; juicy blueberries punctuate every mouthful with bright acidity and color. The result is tender in the middle with slightly crisp, buttery edges — satisfying enough to feel like a treat but wholesome enough to eat every day. What makes this recipe work is its simple balance of ratios and technique. Two cups of milk to two cups of oats gives a soft but not wet bake, while two eggs and a touch of baking powder add lift and structure so the casserole slices cleanly. Using mashed banana rather than all sugar keeps added sweetener modest and adds moisture without oil. It’s an ideal recipe for busy households, weekend brunches, or batch-cooking: assemble ahead, bake in the morning, or bake once and rely on quick reheats for breakfasts all week. ## Recipe Information - Prep Time: 15 minutes - Cook Time: 35 minutes - Total Time: 50 minutes - Servings: 6 - Difficulty: Easy - Category: Baking ## Ingredients ### Combine wet and dry, fold in fruit - 1 cup fresh or frozen blueberries ### Mix the dry ingredients - 2 cups rolled (old-fashioned) oats - 1 tbsp baking powder - 1 tsp ground cinnamon - 1/2 tsp fine sea salt ### Whisk together the wet ingredients - 2 cups milk (dairy or unsweetened plant milk) - 2 large large eggs - 1/4 cup maple syrup (or honey) - 1 cup mashed ripe banana (or applesauce) ### Preheat oven and prepare pan - 2 tbsp unsalted butter, melted (or coconut oil) ## Instructions ### 1. Preheat oven and prepare pan Preheat the oven to 375°F (190°C). Generously grease an 8x8-inch (20x20 cm) baking dish with the melted butter (or coconut oil) so the casserole releases easily and the edges crisp during baking. ### 2. Mix the dry ingredients In a large bowl, combine the rolled oats, baking powder, ground cinnamon, and sea salt. Stir well so the leavening and spices are evenly distributed throughout the oats. ### 3. Whisk together the wet ingredients In a separate bowl, whisk the milk, eggs, maple syrup, and mashed banana until smooth. The banana adds natural sweetness and moisture — if using applesauce, the texture will be slightly lighter. ### 4. Combine wet and dry, fold in fruit Pour the wet mixture into the bowl with the dry ingredients and stir until fully combined. Gently fold in the blueberries, leaving a few to sprinkle on top for a pretty finish. ### 5. Bake until set Transfer the batter to the prepared baking dish, smoothing the top. Bake for 30–40 minutes, or until the center is set and the top is lightly golden — a toothpick inserted near the center should come out mostly clean with a few moist crumbs. ### 6. Cool, slice, and serve Let the casserole rest for 10 minutes to finish setting, then slice into 6 portions. Serve warm with yogurt, milk, a drizzle of extra maple syrup, or a sprinkle of toasted nuts; refrigerate leftovers and reheat individual slices. ## Nutrition Estimated nutrition per serving (about 1 cup): - Calories: 274 kcal - Protein: 6.7 g - Carbohydrates: 40 g - Fat: 10.7 g - Saturated Fat: 5.2 g - Trans Fat: 0 g - Fiber: 3.8 g - Sugar: 15.3 g - Added Sugars: 8.2 g - Cholesterol: 13 mg - Sodium: 210 mg - Potassium: 353 mg - Calcium: 134 mg - Iron: 1.7 mg - Vitamin D: 0 mcg ## Tips ### Use old-fashioned oats Rolled (old-fashioned) oats hold their texture during baking; quick oats will break down and make the casserole too dense and gummy. ### Toss frozen berries If using frozen blueberries, fold them in straight from the freezer and toss with a teaspoon of flour to reduce bleeding into the batter. ### Check center doneness Insert a toothpick near the center — it should come out with a few moist crumbs, not raw batter; underbaked centers will firm up as the casserole rests for 10 minutes. ### Grease for crisp edges Generously coat the baking dish with melted butter or coconut oil to encourage golden edges and easy release when slicing. ### Adjust sweetness last Taste the mashed banana and account for its sweetness before adding maple syrup; reduce syrup if your bananas are very ripe. ## Variations and Substitutions ### Gluten-free swap Use certified gluten-free rolled oats to keep the same texture and avoid cross-contamination for celiac or gluten-sensitive eaters. ### Apple-cinnamon twist Replace mashed banana with 1 cup unsweetened applesauce and fold in 1 cup diced tart apple plus a pinch of ground cloves for a fall-friendly flavor. ### Nutty protein boost Stir 1/3 cup chopped toasted walnuts or pecans into the batter and sprinkle more on top for crunch; swap half the milk for plain Greek yogurt to increase protein and tang. ### Vegan egg-free version Use a flax 'egg' (1 tbsp ground flax + 3 tbsp water per egg) and substitute an extra 1/4 cup plant milk for a fully vegan casserole, though baking time may lengthen slightly. ## Notes This baked oatmeal is a family-friendly, healthy breakfast that shines as a weekend brunch or a weekday make-ahead. Expect a lightly sweet, chewy center and crispy edges — great served warm with yogurt or a splash of milk. ### Storage and Make-Ahead Cool the casserole completely before covering and refrigerating; it will keep well for up to 4 days. For longer storage, slice and freeze individual portions wrapped in plastic and placed in a zip-top bag for up to 3 months. Reheat frozen slices in the microwave for 60–90 seconds or in a 325°F (160°C) oven for 10–15 minutes to revive the texture; add a splash of milk if you want a creamier result. ### Serving Suggestions Serve warm slices with a dollop of Greek yogurt or a spoonful of cultured crème fraîche and a drizzle of maple syrup for richness and tang. Pair with a simple green apple salad or a couple of soft scrambled eggs for extra protein, and offer hot coffee or a bright lemony tea to cut through the sweetness. ## Frequently Asked Questions ### Can I use quick oats instead of rolled oats? You can, but quick oats absorb liquid faster and will yield a denser, porridge-like texture rather than sliceable squares; reduce baking time slightly and expect a softer set. ### Do I have to use banana — what about applesauce? Applesauce is a fine substitute and will produce a lighter texture; if you want more banana flavor without as much moisture, use one mashed banana plus 1/2 cup applesauce. ### Why did my casserole come out soggy in the middle? Sogginess usually means it was underbaked or had excess liquid (overripe banana, too much milk). Bake until the center registers mostly set and allow the casserole to rest for 10–15 minutes off the heat to finish firming up. ### Can I double the recipe? Yes — bake in a 9x13-inch dish and expect a slightly longer bake time (about 40–50 minutes); check doneness with a toothpick and rotate the pan halfway through for even browning. ### How do I prevent blueberry staining? To limit bleeding, either use fresh berries, fold frozen berries in while still frozen, or toss berries with a teaspoon of flour or a light dusting of cornstarch before adding them to the batter. ## Related Recipes and Guides - [Cloud Bread Sandwiches](https://www.topshelf.recipes/recipes/cloud-bread-sandwiches) - [Honey Mustard Chicken Nuggets](https://www.topshelf.recipes/recipes/honey-mustard-chicken-nuggets-baked) - [Cheddar Jalapeño Corn Muffins](https://www.topshelf.recipes/recipes/cheddar-jalapeno-corn-muffins) - [Basque Burnt Cheesecake](https://www.topshelf.recipes/recipes/basque-burnt-cheesecake-salted-caramel) - [30-Minute Sticky Baked Honey Garlic Chicken Thighs with Crisp Edges](https://www.topshelf.recipes/recipes/30-minute-sticky-baked-honey-garlic-chicken-thighs-crisp-edges) - [Lemon Butter Salmon](https://www.topshelf.recipes/recipes/lemon-butter-salmon) - [Baking Soda and Tenderized Beef](https://www.topshelf.recipes/articles/baking-soda-and-meat) - [Gluten-Free Weeknight Grilling Plan](https://www.topshelf.recipes/articles/gluten-free-weeknight-grilling-plan) - [Low-Fat Grill Swaps for Big Flavor](https://www.topshelf.recipes/articles/low-fat-grill-swaps-big-flavor)