Coffee Cake Baked Oatmeal (With Walnut Streusel Topping)

Why You’ll Love This Baked Oatmeal Recipe

I’ve made countless versions of baked oatmeal over the years, and it remains my favorite breakfast because it’s dependable, practically foolproof, flexible, and fits just about any occasion! It works equally well for quiet weekdays and relaxed brunches, delivering cozy coffee cake flavor without feeling like dessert. I’ve served some version of baked oatmeal to nearly every type of guest, and it never feels like a compromise – you can adjust the ingredients based on what you have, make it dairy-free or egg-free, and it still bakes up beautifully. For a more portable option, my Individual Baked Oatmeal Cups are always a hit.

What makes this version stand out is the walnut streusel topping, which bakes into a tender, cake-like oatmeal base and adds just enough contrast for true coffee cake flavor without overpowering the oats. It’s also ideal for entertaining – you can assemble everything the night before, refrigerate it, and bake it in the morning while you make coffee. If you enjoy cozy, make-ahead breakfasts for guests or busy weeks, my Slow Cooker Apple Pie Steel-Cut Oats are another comforting option that fits right into that rhythm.

Ingredients You’ll Need

Baked Oatmeal Base

• Butter, plant butter, or coconut oil: For greasing the baking dish and preventing sticking
• Eggs: Help the oatmeal set and give it structure. Swap: ripe banana, applesauce, or pumpkin purée if you prefer an egg-free option.
• Milk or unsweetened plant milk: Keeps the oatmeal moist and creamy as it bakes.
• Maple syrup or brown sugar: Lightly sweetens the oatmeal without overpowering it.
• Pure vanilla extract: Adds warmth and rounds out the flavors.
• Old-fashioned oats: Create a hearty base that bakes up soft, not mushy.
• Aluminum-free baking powder: Helps lift the oatmeal so it doesn’t feel dense.
• Ground cinnamon: Brings warmth and classic coffee cake notes.
• Ground nutmeg: Adds subtle depth and balance.
• Sea salt: Sharpens and enhances all the flavors.

Walnut Streusel Topping

• Finely chopped walnuts or walnut meal: Add texture and richness. You can swap for pecans or coconut flakes if needed/desired.
• Quick-cooking oats: Help form a cohesive, crumbly topping.
• Brown sugar: Adds caramel-like sweetness to the topping.
• Flour: Helps bind the streusel. Use whole wheat, gluten-free blend, or Paleo-friendly flour if needed/desired.
• Ground cinnamon: Reinforces the warm spice profile.
• Melted unsalted butter, plant butter, or coconut oil: Brings the streusel together so it’s moist and clumpy.

Optional Powdered Sugar Glaze

• Powdered sugar
• Milk or water

How to Make Coffee Cake Baked Oatmeal

Step 1: Preheat your oven and grease an 8×8-inch or 9-inch baking dish. (You can also use a cast iron skillet or gratin dish for a different presentation.) In a large bowl, beat the eggs, then stir in the milk, sweetener, and vanilla.

Step 2: Add the oats, baking powder, cinnamon, nutmeg, and salt, and mix until everything is well combined.

Step 3: Pour the mixture into the prepared dish and spread it evenly. This can be done the night before and refrigerated.

Step 4: In a separate bowl, combine the walnuts, oats, sugar, flour, cinnamon, and melted butter. Mix until evenly moistened, then sprinkle over the oatmeal.

Step 5: Bake until the top is golden and the center is just set. Let it cool briefly so it firms up before serving. Add the glaze if you like and enjoy!

How to Store and Reheat Coffee Cake Baked Oatmeal

Store leftovers covered in the refrigerator for up to 4-5 days. To reheat, warm individual portions in the microwave with a splash of milk to keep the oatmeal soft and moist, or reheat the entire dish in a low oven until warmed through.

This baked oatmeal also freezes well; thaw overnight in the fridge before reheating.

Recipe FAQs

This oven-baked oatmeal is cozy, flexible, and designed to make mornings easier without sacrificing flavor. Try it once, and it’s likely to become a regular in your breakfast rotation. I’d love to hear how you serve it or what toppings you add.