Equipment
* optional
Ingredients
Dry Ingredients
- 250 g rolled oats, whole old-fashioned
- 6 g baking powder
- 4 g ground cinnamon
- 1 g ground nutmeg
- 2 g fine sea salt
Wet Ingredients
- 400 ml whole milk, chilled or room temperature
- 2 egg, room temperature
- 80 ml pure maple syrup
- 45 g unsalted butter, divided: 40g melted and cooled, 5g softened for dish
- 5 ml vanilla extract
Fruit Add-ins
- 1 apple, peeled, cored, and diced into 1 cm cubes
- 150 g fresh blueberries, rinsed and dried thoroughly
Nutrition (per serving)
Nutrition is estimated per serving. Nutrients without complete source data are omitted.
Full nutrition
- Calories
- 355 kcal
- Protein
- 10 g
- Carbohydrates
- 51 g
- Fat
- 13 g
- Fiber
- 6 g
- Sugar
- 20 g
- Zinc
- 2.3 mg
- Water
- 101 g
Sources: Aggregated Public Data, USDA FoodData Central
Method
Preheat the oven to 190°C (375°F) with the baking rack positioned in the center.
Grease the bottom and sides of the baking dish (20x20 cm / 8x8 inch) evenly using the reserved 5g of softened unsalted butter and a pastry brush.
In a large mixing bowl, combine the rolled oats, baking powder, ground cinnamon, ground nutmeg, and fine sea salt, then whisk until the spices and leavening are uniformly distributed throughout the oats.
In a medium mixing bowl, combine the whole milk, eggs, pure maple syrup, 40g of melted unsalted butter, and vanilla extract, then whisk vigorously until the eggs are completely broken down and the liquid is emulsified.
Add the diced apple and 75g of the fresh blueberries to the dry oat mixture in the large mixing bowl, then fold gently with a silicone spatula until evenly scattered.
Transfer the oat and fruit mixture into the prepared baking dish, level the surface with the silicone spatula, pour the wet milk mixture evenly across the top, and scatter the remaining 75g of fresh blueberries over the surface.
Transfer the baking dish to the center rack of the oven and bake at 190°C (375°F) for 35 to 40 minutes, until the top is golden brown, the edges are bubbling, and an instant-read food thermometer inserted into the center reads at least 71°C (160°F) to ensure the egg custard is fully and safely cooked.
Remove the baking dish from the oven and set it onto a wire cooling rack to rest for 10 minutes, allowing the custard to firm up for neat slicing before serving warm.
Chef's Notes
- To enhance nutty depth, spread the rolled oats across a dry baking sheet and toast at 175°C (350°F) for 8 to 10 minutes before combining with spices.
- For an indulgent dessert presentation, serve warm slices topped with a scoop of vanilla bean ice cream or a spoonful of lightly sweetened crème fraîche.
- Do not substitute instant or quick-cooking oats for traditional rolled oats; smaller processed flakes absorb moisture too rapidly and result in a gummy texture.
- If using frozen blueberries, keep them completely frozen until the exact moment they are added to the dish to minimize bleeding color into the batter.
Storage
Refrigerator: 5 days — Store in an airtight container at or below 4°C (40°F) within two hours of baking.
Freezer: 3 months — Slice into portions, wrap securely, and store in a freezer-safe container.
Reheating: Reheat refrigerated portions in an oven preheated to 175°C (350°F) for 12 to 15 minutes, or in a microwave on high for 60 to 90 seconds, until thoroughly heated and the internal temperature reaches at least 74°C (165°F).
Troubleshooting
The center of the bake is loose, wet, and does not hold its shape when sliced.
Cause: The bake was undercooked or the oven temperature ran cooler than indicated.
Fix: Return the dish to the oven at 190°C (375°F) for an additional 8 to 10 minutes until the center reaches 71°C (160°F).
Prevention: Verify your oven calibration using an independent oven thermometer and rely on an instant-read probe rather than visual cues alone.
The top surface is darkening quickly while the internal custard remains unbaked.
Cause: The dish is placed too close to the top heat element or the oven produces excessive top heat.
Fix: Tent the baking dish loosely with aluminum foil for the remainder of the bake time to block direct radiant heat.
Prevention: Position the baking dish on the center or lower-middle rack.
Blueberries burst and turn the entire oat mixture an unappealing grayish-purple.
Cause: Berries were mixed too aggressively into the oats, rupturing skins before baking.
Fix: Cannot be fixed once baked, though flavor and nutrition remain completely unaffected.
Prevention: Fold fruit gently with a silicone spatula and scatter half directly over the top rather than mixing throughout.
Cultural Context
Baked oatmeal originated in Pennsylvania Dutch communities in the eastern United States, where it was developed as an economical, hearty breakfast casserole capable of feeding early-rising farm families. In contemporary American cuisine, the dish has evolved into a versatile brunch and dessert staple, bridging the comfort of rustic whole grains with the delicate structure of fruit crumbles and bread puddings.
