Total Time: 50 minutes (10 minutes prep, 40 minutes baking)
Serving Size: 6 generous squares
Difficulty Level: Easy
Dietary Tags: Vegetarian, Can be made gluten-free & dairy-free
A Cozy, Make-Ahead Breakfast
This Cinnamon-Apple Walnut Baked Oatmeal is the ultimate hands-off breakfast. Imagine the comforting aromas of apple pie and toasted walnuts wafting from your oven, but in the form of a nourishing, satiating dish. Unlike stovetop oatmeal, this bake emerges golden and sliceable—perfect for meal prep, weekend brunches, or a quick weekday reheat. It’s wonderfully adaptable, endlessly comforting, and sure to become a staple in your kitchen.
Ingredients
For the Oatmeal Base:
2 cups (200g) old-fashioned rolled oats (use certified gluten-free if needed)
1 tsp baking powder
½ tsp fine sea salt
1 ½ tsp ground cinnamon
¼ tsp ground nutmeg
For the Wet Mixture:
1 large apple (like Honeycrisp or Granny Smith), peeled and diced (about 1 ½ cups)
⅔ cup (65g) chopped walnuts, divided
1 ¾ cups (415ml) milk (dairy, almond, or oat milk all work)
⅓ cup (80ml) pure maple syrup or honey
1 large egg (or 1 flax egg for vegan: 1 tbsp ground flax + 2.5 tbsp water)
2 tbsp melted coconut oil or unsalted butter, cooled slightly
1 tsp pure vanilla extract
For Serving (Optional):
A drizzle of maple syrup or yogurt
A splash of cold milk or cream
Equipment
8×8 inch (20×20 cm) baking dish
Mixing bowls (one medium, one large)
Whisk
Spatula
Measuring cups and spoons
Step-by-Step Instructions
Step 1: Prep & Preheat (5 minutes)
Preheat your oven to 375°F (190°C).
Lightly grease your 8×8 inch baking dish with oil or butter.
Prepare your flax egg if using (mix and let sit for 5 minutes). Otherwise, crack your regular egg into a medium bowl.
Step 2: Combine Dry Ingredients (2 minutes)
In a large mixing bowl, whisk together the rolled oats, baking powder, salt, cinnamon, and nutmeg until evenly combined. This ensures the leavening and spices are distributed throughout the bake for perfect flavor in every bite.
Step 3: Combine Wet Ingredients (3 minutes)
To the medium bowl with your egg (or prepared flax egg), add the milk, maple syrup, melted (and cooled) coconut oil, and vanilla extract. Whisk vigorously until the mixture is completely smooth and emulsified.
Step 4: Assemble the Bake (3 minutes)
Add the diced apple and half of the chopped walnuts (reserve the rest for the top) to the bowl with the dry oats. Stir to coat the apple and nuts in the spiced oat mixture.
Pour the wet mixture over the dry ingredients. Use a spatula to fold everything together until no dry patches remain. The mixture will be quite liquid—this is correct!
Carefully pour the mixture into your prepared baking dish. Use the spatula to spread it evenly. Sprinkle the remaining chopped walnuts over the top.
Step 5: Bake & Test for Doneness (40 minutes)
Place the dish in the center of your preheated oven.
Bake for 35-40 minutes, or until the top is a deep golden brown, the edges are pulling away slightly from the dish, and the center is set (it should not jiggle when you gently shake the pan).
Pro Tip: For a crispier top, you can broil for the final 1-2 minutes, watching carefully to prevent burning.
Step 6: Cool & Serve (10 minutes recommended)
Remove the baked oatmeal from the oven and place the dish on a wire rack.
Let it cool for at least 10 minutes before slicing. This crucial resting time allows the custardy interior to set fully, making it easy to cut into neat squares.
Serve warm directly from the dish.
Serving & Storage
Serving Suggestions:
Serve each square as is, or elevate it with a drizzle of maple syrup, a dollop of Greek yogurt, or a splash of cold milk. It’s delicious warm or at room temperature.
Storage & Reheating:
Refrigerator: Store covered in the baking dish or in an airtight container for up to 5 days.
Freezer: Individually wrap cooled squares and freeze in a sealed container for up to 3 months. Thaw overnight in the fridge or reheat from frozen.
Reheat: Warm squares in the microwave for 60-90 seconds or in a toaster oven/regular oven at 350°F (175°C) for 10 minutes until heated through.
Customize Your Bake!
This recipe is a perfect canvas:
Berry Bliss: Replace the apple with 1 ½ cups of fresh or frozen blueberries or raspberries.
Tropical Twist: Use diced ripe banana and ½ cup shredded coconut instead of apple and walnuts.
Chocolate Chip: Swap walnuts for ½ cup dark chocolate chips.
Pumpkin Spice: Replace the apple with 1 cup of canned pumpkin puree and add a pinch of cloves and ginger.
Nutrition Information
*Estimated values per serving (1/6th of recipe), calculated with 2% dairy milk and without optional toppings.*
Nutrient Amount % Daily Value*
Calories ~320
Total Fat 14g 18%
Saturated Fat 5g 25%
Cholesterol 35mg 12%
Sodium 280mg 12%
Total Carbohydrate 42g 15%
Dietary Fiber 5g 18%
Total Sugars 19g (10g added)
Protein 9g 18%
Calcium 150mg 15%
Iron 2mg 10%
Potassium ~300mg 6%