Sourdough Marble Loaf

There’s something magical about the swirl of a marble loaf. The visual appeal alone is enough to stop anyone in their tracks, but the flavor? That’s where this Sourdough Marble Loaf truly shines. The tender, rich crumb combines the tang of sourdough with the indulgence of cocoa, making it ideal for breakfast, brunch, or even dessert.

If you’re looking for a show-stopping sourdough recipe that’s just as fun to make as it is to slice into, you’ve come to the right place. This loaf is beginner-friendly, naturally leavened, and deeply satisfying.

What Is a Sourdough Marble Loaf?

A marble loaf typically blends two flavors—often vanilla and chocolate—into a swirled, tender crumb. In this version, we use a sourdough base to elevate the flavor profile and add depth. The natural fermentation gives this loaf a slight tang that pairs perfectly with the sweet richness of cocoa.

Think: banana bread meets sourdough meets chocolate cake. It’s moist, rich, and sliceable perfection.

Why You'll Love This Sourdough Marble Loaf

• Stunning presentation – Perfectly marbled interior makes for gorgeous slices.

• Naturally leavened – Uses sourdough starter or discard for flavor and texture.

• Great for gifting – Wrap a loaf in parchment and twine for an elegant, homemade gift.

• Flexible schedule – Long ferment or short proof, depending on your timeline.

• Versatile flavor – Enjoy it as breakfast, snack, or dessert.

Ingredients

For the Base Batter:

• 200g all-purpose flour

• 100g sourdough starter (active or discard)

• 100g whole milk (room temperature)

• 100g granulated sugar

• 2 large eggs

• 75g neutral oil (vegetable, avocado, or melted coconut oil)

• 1 tsp vanilla extract

• 1 tsp baking powder

• ½ tsp baking soda

• ¼ tsp salt

For the Cocoa Batter:

• 2 tbsp unsweetened cocoa powder

• 1 tbsp milk (for thinning)

• 1 tbsp sugar (optional, for extra sweetness)

Timeline Options

You can make this loaf with either a:

• Quick same-day ferment (with active starter)

• Long overnight ferment (with discard)

We’ll go over both methods so you can choose what fits your schedule best.

Instructions

Step 1: Mix the Wet Ingredients

In a large mixing bowl, whisk together:

• Eggs

• Sugar

• Oil

• Milk

• Vanilla extract

• Sourdough starter

Mix until smooth and fully incorporated.

Step 2: Add Dry Ingredients

Sift together flour, baking powder, baking soda, and salt. Gently fold them into the wet mixture using a spatula. Do not overmix.

Step 3: Divide and Flavor

Split the batter evenly between two bowls.

To one bowl, add:

• 2 tbsp cocoa powder

• 1 tbsp milk

• Optional: 1 tbsp sugar

Mix until a smooth chocolate batter forms.

Step 4: Layer and Swirl

Grease and line a standard loaf pan. Alternating between vanilla and chocolate batter, dollop spoonfuls into the pan. Once filled, use a butter knife to gently swirl the batters together—don’t overdo it!

Step 5: Ferment or Proof

Option 1: Long Ferment

• Cover and let rest at room temp for 1 hour.

• Then refrigerate overnight (8–12 hours).

• In the morning, let come to room temp for 1 hour before baking.

Option 2: Quick Proof

• If using active starter, let the loaf rise at room temperature for 3–4 hours, or until slightly puffy.

Step 6: Bake

Preheat oven to 350°F (175°C). Bake for 45–55 minutes, or until a toothpick inserted comes out clean. Let cool in the pan for 10 minutes, then remove and cool fully on a wire rack.

Tips for Perfect Marble Swirls

• Use two spoons or small scoops to alternate batters neatly.

• For bold contrast, keep cocoa layer thicker and swirl gently.

• Don’t overmix the two batters once in the pan.

• Bake in a light-colored loaf pan to avoid over-browning.

Slicing and Serving

Let the loaf cool completely before slicing for the cleanest swirls. Serve plain, or with a spread of butter, Nutella, or cream cheese for extra indulgence.

It pairs beautifully with morning coffee or an after-dinner glass of red wine.

Storage and Freezing

• Room temp: Wrap tightly and store for up to 3 days.

• Fridge: Store in an airtight container for up to 1 week.

• Freezer: Wrap slices individually and freeze up to 2 months.

Troubleshooting

Loaf didn't rise much?
Your starter may be sluggish. Use a float-tested, active starter for quicker proofing.

Batter too thick?
Try adding an extra tablespoon of milk to the cocoa portion.

Swirl not defined?
Use a more distinct zig-zag or figure-eight motion with your knife.

Add-Ins and Variations

• Chocolate chips – Fold in ½ cup for melty bursts of chocolate.

• Zest or spice – Add orange zest, cinnamon, or espresso powder for extra flavor.

• Nutty crunch – Swirl in chopped walnuts or pecans.

FAQs

Can I make this 100% whole wheat?
Yes, but the loaf will be denser. Try half whole wheat and half all-purpose for best texture.

Can I use sourdough discard straight from the fridge?
Yes, for the long ferment version, you can use cold discard. Just extend the fermentation.

Is this loaf sweet or savory?
Sweet, but not overly so. It’s similar in sweetness to banana bread.

A Beautiful Gift Idea

This loaf makes a lovely gift wrapped in parchment paper and tied with twine. Add a handwritten note and give it to neighbors, teachers, or friends for holidays or special occasions.

Final Thoughts

This Sourdough Marble Loaf is a celebration of contrasts—light and dark, sweet and tangy, soft and sturdy. Whether you’re just beginning your sourdough journey or looking to use up extra discard in something more exciting than pancakes, this loaf checks every box. It’s as gorgeous as it is delicious.

Slice it, savor it, and don’t forget to take a picture before it’s gone.