Cozy Sourdough Baked Oatmeal (One Bowl)

Name: Sourdough Baked Oatmeal
Prep time: 5 min
Cook time: 45 min
Total time: 50 min
Ingredients: 115 g Butter ((melted)); 1 Egg ((large)); 10 g Vanilla Extract ((or 5g of vanilla paste)); 200 g Milk ((any milk is fine)); 200 g Sourdough Starter; 150 g Brown Sugar ((reduce if you want to)); 300 g Rolled Oats; 12 g Baking Powder; 6 g Salt; 6 g Cinnamon ((optional))

ByKate Freebairn Modified: December 4, 2025

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This sourdough baked oatmeal is a warm, hearty breakfast that comes together in one bowl using a scale so you have minimal dishes!! It's moist enough that it doesn't need a glaze or cream, but firm enough that you can eat it with one hand if you need to. You can make it with sourdough starter or discard and add in any flavors you like!

Sliced sourdough baked oatmeal in squares on parchment paper with one slice on a plate topped with yogurt and apple butter for serving.

This baked oatmeal is delicious just as it is, but also perfect for adding your fave flavors to as well. We love topping with a bit of yogurt and some homemade apple butter. I've got a list of fun flavors further down the post if you'd like some ideas to experiment with.

Why You'll Love This Recipe!

Make-Ahead Breakfast - Bake once, cool, slice, and keep ready for quick weekday breakfasts. It stores perfectly in the fridge and tastes great warmed or cold. These baked oats make the perfect grab and go breakfast. I love having a batch cut up in the fridge, along with a jar of these sourdough breakfast cookies on the counter.

One Bowl Recipe - Everything mixes together in a single bowl and when you use a scale, you don't even have to fuss with measuring cups. Cleanup is so easy!

Totally Customizable - Enjoy the baked oats as-is, or add in some of your favorite fruit, nuts, spices, or chocolate if you want to change it up.

Pouring maple syrup over a slice of sourdough baked oatmeal that's topped with yogurt.

Ingredients

Butter - Let the butter cool slightly before mixing. As I mention in my look inside the Pantry Mama test kitchen, I always prefer salted butter (and homemade butter), but unsalted works fine too.
Egg - One large egg helps bind everything so the squares hold together well.
Vanilla Extract - Vanilla paste works too if that’s what you keep in the pantry.
Milk - Any milk is fine, including dairy-free. Use what you have on hand.
Sourdough Starter - Active starter or discard both work. I've used active sourdough starter, but you can definitely sub with discard if you have a lot on hand!
Brown Sugar - Use the full amount for a sweeter bake or reduce it if you'd like it a little less sweet.
Rolled Oats - Regular rolled oats are best. Quick oats will change the texture, and steel cut oats won't work.
Baking Powder
Salt
Cinnamon - Optional, but adds a warm hint of spice, and helps enhance the flavors.

How to Make Cozy Sourdough Baked Oatmeal

Start by preheating your oven to 185ºC (365ºF). Line a 9" x 9" baking pan with parchment paper (or spray well with cooking oil).

In a large mixing bowl, whisk together the melted butter, egg, vanilla extract and milk.

Then add your sourdough starter and whisk this until the mixture is smooth.

Two photos to show mixing the wet ingredients, including sourdough starter, in a bowl to make sourdough baked oatmeal.

Now add in the brown sugar, rolled oats, baking powder, salt and cinnamon and stir together until all of the rolled oats are wet and everything is well combined.

Two photos to show adding dry ingredients to wet ingredients in a mixing bowl to make the batter for sourdough baked oatmeal.

Pour the oatmeal mixture into the pan you prepared and place into the oven for 45 minutes at 185ºC (365ºF).

Batter emptied from mixing bowl into baking pan to make sourdough baked oatmeal.

Once the top is golden and the edges are starting to crisp, remove from the oven and allow to cool in the pan for around 10 minutes.

You can serve warm or allow to cool fully and slice into squares to package for the fridge or freezer.

Fresh baked sourdough baked oatmeal in pan on wooden table.

Kate's Recipe Tip

If you're adding other flavors into this recipe like diced apples, raisins, frozen fruit etc. (anything that increases the volume of this recipe) I would increase the size of your pan from 9" x 9" to 9" x 13" just to ensure the baked oatmeal does not overflow when baking.

Flavor Variations for Sourdough Baked Oatmeal

While this baked oatmeal is delicious just as it is, you can easily mix in all kinds of add-ins to change up the flavor. Here are some of my family’s favorite combinations. Just fold your add-ins straight into the batter after mixing, and use a larger pan, like a 9" x 13".

Apple Cinnamon - Stir in small diced apples and a little extra cinnamon for a classic, warm flavor.
Blueberry Lemon - Add fresh or frozen blueberries and a bit of lemon zest. The tangy lemon pairs beautifully with the sweet berries.
Chocolate Chip - Fold in chocolate chips or chopped dark chocolate for a sweeter breakfast. Kids love this one.
Banana Walnut - Mix in mashed ripe banana and a handful of chopped walnuts (pecans would be good too). It bakes up extra soft and naturally sweet.
Peanut Butter Swirl - Add a few spoonfuls of slightly warmed peanut butter and swirl it through the batter. Chocolate chips are great here too.
Cranberry Orange - Similar to this orange cranberry sourdough bread, you can add dried cranberries and a bit of orange zest for a fresh, citrusy take that feels great around the holidays.

You may also enjoy this pumpkin pie baked oatmeal recipe that includes pumpkin puree and a maple cream cheese glaze for a festive fall flavor.

How to Store + Freeze

Store at Room Temperature - After the baked oatmeal cools, keep it covered in the pan or move the pieces into an airtight container. It stays nice and fresh on the counter for about two days.

Refrigerate - For longer storage, pop the cooled slices into the fridge where they’ll keep for up to five days. A quick zap in the microwave brings back that soft, warm texture.

Freeze for Later - Once fully cooled, cut the oatmeal into squares and wrap each one tightly before placing them in a freezer-safe bag or container. They’ll freeze well for up to three months. Thaw in the fridge overnight or warm them from frozen, adding a little extra time until they’re soft and ready to eat.