Ingredients
- 2.5 cups rolled oats (old-fashioned, not quick or instant)
- 2 tsp baking powder
- 1 tsp ground cinnamon
- 0.5 tsp kosher salt
- 2 large eggs
- 1.75 cups milk (whole or 2%, or unsweetened plant milk)
- 0.33 cup maple syrup or honey
- 2 tbsp melted butter or neutral oil
- 1 tsp vanilla extract
- 1.5 cups mixed berries (fresh or frozen, unthawed if frozen)
- 0.5 cup chopped walnuts or pecans (optional)
- 1 tbsp butter or oil spray (for greasing the dish)
Instructions
- Preheat oven to 375°F (190°C). Grease an 8x8-inch or 9x9-inch baking dish thoroughly with butter or oil spray — this matters more than you'd expect since the baked oatmeal can stick stubbornly to an under-greased dish, making clean portioning difficult.
- In a large bowl, whisk together the dry ingredients: rolled oats, baking powder, cinnamon, and salt. Make sure the baking powder is evenly distributed through the oats — clumped baking powder creates uneven texture and occasional bitter spots in the finished bake.
- In a separate bowl, whisk together the eggs, milk, maple syrup or honey, melted butter, and vanilla extract until fully combined and slightly frothy. The eggs are what give baked oatmeal its sliceable, cohesive structure — this is the key difference from simply baking oats with milk alone, which produces a much looser, crumblier result.
- Pour the wet mixture into the bowl with the dry ingredients and stir until just combined — you want everything evenly moistened but don't need to overmix. Fold in the berries and nuts if using, reserving a small handful of berries to scatter on top for visual appeal.
- Pour the mixture into the prepared baking dish and spread evenly with a spatula. Scatter the reserved berries and any extra nuts across the top. The mixture will look quite liquid at this stage — that's correct, the oats will absorb the liquid and set firmly during baking.
- Bake for 35 to 40 minutes, until the top is golden brown, the edges have pulled slightly away from the sides of the dish, and the center is set rather than jiggly. A toothpick inserted in the center should come out clean or with just a few moist crumbs, not wet batter.
- Remove from the oven and let cool in the dish for at least 20 minutes before slicing — cutting into it too early causes it to fall apart rather than slice cleanly, since the structure is still firming up as it cools. For best texture retention, let it cool closer to 30 minutes if you have the time.
- Slice into 6 even portions. Store in an airtight container, either as a single layer with parchment between portions or in individual containers. Refrigerate once fully cooled. For longer storage, wrap individual slices tightly in plastic wrap before freezing — this prevents both freezer burn and the slices from sticking together.
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Storage and Safety Notes
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View on AmazonCool completely in the baking dish for at least 20 minutes before slicing and portioning — sealing it warm traps steam and accelerates spoilage. Refrigerate in an airtight container for 5 to 6 days at 40°F (4°C) or below; this dish contains eggs, so it follows standard egg-dish storage guidance per USDA FoodKeeper (foodkeeper.usda.gov). Freezes well for up to 2 months — wrap individual portions tightly in plastic wrap, then place in a freezer bag. Reheat refrigerated portions for 60 to 90 seconds in the microwave; reheat frozen portions by thawing overnight in the fridge first, then microwaving 90 seconds to 2 minutes. A splash of milk before reheating restores moisture if the portion seems dry.
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