One-Bowl Sourdough Chocolate Cake

Ingredients — measured and specific

Dry and wet ingredients

• All-purpose flour: 220 g (1 3/4 cups) — spoon and level for accuracy.
• Cocoa powder: 60 g (2/3 cup) unsweetened Dutch-processed for deeper flavor; swap to natural for lighter acidity but reduce baking soda by 1/4 tsp if using.
• Granulated sugar: 200 g (1 cup) — for balanced sweetness; can use 150 g sugar + 50 g brown sugar for moisture and caramel notes.
• Baking soda: 1 tsp — activates with starter acidity.
• Salt: 1/2 tsp fine sea salt.
• Large eggs: 2, room temperature for emulsification and lift.
• Whole milk or buttermilk: 120 ml (1/2 cup); use buttermilk or add 1 tsp lemon juice to milk for tang and tender crumb.
• Neutral oil: 80 ml (1/3 cup) or melted unsalted butter for richer flavor. Oil yields moister, more shelf-stable cake.
• Active sourdough starter: 150 g (roughly 2/3 cup) at 100% hydration, recently fed and bubbly. If starter is 120% hydration, reduce milk by 10–15 ml.
• Vanilla extract: 1 tsp for aroma.
• Optional add-ins: 60–80 g chocolate chips or espresso powder 1 tsp to deepen chocolate flavor.

Notes on ingredient scaling and swaps
Use weight if possible for repeatable results. If converting starter amount, maintain roughly 25–30% starter relative to total flour weight for proper leaven and acid balance. For gluten-free, substitute a blend that includes xanthan gum and reduce liquid by 10–15%; expect denser crumb and longer bake time.

Equipment and bowl selection

Essential tools

• One large mixing bowl (3–4 L): stainless steel, glass, or heatproof ceramic; choose a wide rim for easier mixing and scraping.
• Whisk and rubber spatula: whisk to combine dry ingredients; spatula to fold wet into dry and scrape bowl clean.
• Measuring scale: accurate to 1 g for consistent results.
• 8- or 9-inch round cake pan or 20 cm square: line base with parchment and grease sides to release a moist crumb cleanly.
• Oven thermometer and probe: ensure oven reads true; internal cake temp target is 96–98°C (205–208°F) when done.
• Cooling rack: promotes airflow; prevents soggy bottom.

Alternative gear and why it matters
Use a heavy-bottomed pan to avoid hot spots that burn chocolate. A splash of boiling water steamed briefly in the oven before placing the pan can stabilize oven humidity for a slightly more tender crumb. Avoid electric mixers for this method; hand mixing in one bowl preserves tender crumb and prevents over-aeration which can collapse with sourdough acidity. If using a dark non-stick pan, reduce oven temperature by 15–20°C and lengthen time slightly; check doneness earlier to prevent overbrowning.

Starter readiness and prep timing

Starter activity check
Feed your starter 4–8 hours before mixing so it peaks and is bubbly at mix time. Look for doubling in volume, a domed surface, and a network of air bubbles. Avoid using starter immediately after feeding when it is still very thin and aggressively acidic; aim for peak to slightly receding for balance between lift and flavor.

Room temperature and ingredient prep
Remove eggs and milk from the fridge 30–60 minutes before starting to reach room temperature; this improves emulsification and oven spring. Sift cocoa powder with baking soda to remove lumps and ensure even distribution. If using melted chocolate, cool to warm (about 40°C) before adding to avoid cooking the eggs. For quicker prep, whisk dry ingredients in the bowl first, then pour liquids over and fold once or twice until just combined — do not overmix.

Timing chart

• Starter feed: T minus 6–8 hours.
• Preheat oven and prep pan: T minus 30 minutes.
• Bring eggs/milk to room temp: T minus 30–60 minutes.
• Mix and bake: T equals 0.

Use this schedule to ensure starter is predictable and ingredients are ready simultaneously for a smooth one-bowl workflow.

One-bowl mixing and batter texture (mixing & baking)

Step-by-step one-bowl mixing
Whisk the dry ingredients together in the bowl: flour, sifted cocoa, sugar, baking soda, and salt until uniform. Make a shallow well and add eggs, milk, oil (or melted butter), vanilla, and the active starter. Use a rubber spatula or wooden spoon to fold gently: mix with broad strokes from the bottom to the top until no streaks of flour remain. Aim for a batter that is thick but pourable; if it resembles a scoopable brownie batter, add 10–20 ml milk to loosen slightly. If it is overly thin, add 1–2 tbsp flour and fold carefully to avoid toughness.

Folding technique and air retention
Limit mixing to 20–30 strokes after liquids are added to protect gluten structure. The starter provides both acid and leavening when combined with baking soda; avoid vigorous whisking that entraps large air bubbles which can collapse in the oven. Transfer batter to the prepared pan using the spatula and level by gently tapping the pan on the counter twice to remove large trapped air pockets.

Bake placement and immediate oven handling
Place the pan in the center of the preheated oven. Do not open the door for the first 20 minutes to prevent oven spring collapse. If top browning too quickly, tent with foil after 15 minutes and continue baking. For a fudgier center, bake until the edges are set and the center registers 95–98°C on a probe; for a more cake-like crumb, aim for 98–102°C.

Baking times, temperatures, and tests for doneness

Standard bake settings
Preheat oven to 175°C (350°F) for a light crumb or 160°C (320°F) for a moister, denser crumb using convection adjusters. Bake time for an 8–9 inch round pan typically runs 32–42 minutes depending on pan depth and oven accuracy. Use an oven thermometer to confirm oven temperature before baking.

Doneness methods

• Toothpick test: Insert near center; moist crumbs that cling are acceptable—avoid wet batter.
• Internal temp: Target 96–98°C (205–208°F) for a moist set crumb; higher temps yield drier cake.
• Edge pull: Cake edges will slightly pull from the pan when done.

Adjustments for altitude and oven type
At high altitude, reduce baking soda by 1/8–1/4 tsp and increase liquid by 5–10% to counter rapid expansion and dryness. For glass or dark pans reduce oven temperature by 15–20°C and lengthen time; check early to prevent overbrowning. When using convection, reduce temperature by 15–20°C and monitor time closely—convection speeds browning and can dry the cake if left at the same temp as conventional ovens.

Cooling, unmolding, and finishing options

Cooling protocol for structure
Let the cake cool in the pan on a wire rack for 15–20 minutes; this lets residual heat finish setting the crumb while preventing immediate steam sogginess. After 15–20 minutes, run a thin knife around the edge to ensure release, invert onto the rack, and peel parchment from the base. Cool completely on the rack before slicing or applying frosting to avoid melting and sliding.

Glaze and syrup options
Brush the cooled cake with a simple soaking syrup for added moisture: dissolve equal parts sugar and hot water (or coffee) 1:1 by weight, cool, and brush 1–2 tbsp per cake layer. For a richer finish, pour a chocolate ganache made with 150 g dark chocolate and 120 ml hot cream, stir until glossy and pour over a slightly warm cake for an even drip. Sprinkle flaky sea salt right after ganache to balance sweetness.

Slicing and serving tips
Use a warm, serrated knife wiped clean between cuts for neat slices. Serve slightly warm with whipped cream or a scoop of vanilla ice cream to contrast the chocolate density. For layered presentation, halve horizontally with a serrated cake leveler and spread a thin layer of ganache or salted caramel between layers to reinforce moisture and flavor.

Batter adjustments and troubleshooting during mixing

Common batter issues and fixes
If batter is too thick and dry: add milk in 1 tbsp increments (15 ml) and fold until desired consistency; allow the flour a 1–2 minute rest to hydrate fully. If batter is too thin and slack: fold in 1 tbsp (8–10 g) flour at a time and avoid overmixing to prevent toughness. If you see large lumps of cocoa or flour after initial mixing, use the spatula to press them against the bowl and gently incorporate — do not overwork the batter.

Starter-related problems
If starter smells harshly alcoholic or extremely sour, feed again and wait until a milder, fruity aroma returns; overly acidic starter can curdle batter and inhibit rise. If starter is underactive and batter lacks expected lift, add 1/4 tsp additional baking soda to compensate and bake immediately; expect slightly different crumb texture.

Cracking, sinking, or gummy center fixes
Cracking: usually from oven too hot—reduce temp by 10–15°C next bake. Sinking center: underbaked or over-leavened; check internal temperature target and reduce starter or baking soda next time. Gummy center: underbaked or too much liquid—extend bake time in 3–5 minute increments and confirm with an internal thermometer. For immediate patching, level the top and apply a thin ganache layer which hides texture while adding moisture and flavor.

Storage, reheating, and make-ahead strategies

Short-term storage
Wrap the completely cooled cake tightly in plastic wrap or place in an airtight container at room temperature for up to 2 days. For best texture, keep ungarnished cake at room temp; if frosted with perishable cream or ganache, refrigerate and bring to room temperature before serving to restore tenderness.

Long-term storage
For up to 2 months, slice and wrap pieces individually in plastic wrap and place in a freezer bag; to prevent freezer burn add a layer of aluminum foil. Thaw slices overnight in the refrigerator and bring to room temperature before reheating to preserve crumb integrity.

Reheating and refreshing
Warm single slices in a microwave for 10–15 seconds to revitalize moisture, or reheat a whole small cake in a 150°C (300°F) oven for 8–12 minutes covered with foil to avoid crust hardening. For a fresh-baked feel, brush thawed slices lightly with syrup and warm briefly in the oven to reactivate the sugar and soften the crumb. For plated service, add a warm sauce or scoop of ice cream to refresh mouthfeel and contrast temperature.

Frequently Asked Questions (FAQs)

Can I use a discard starter?
Yes, discard can be used, but expect less leavening and a milder tang. If using discard, increase baking soda by 1/4 tsp and bake immediately. If discard is thin and liquidy, reduce milk by 10–20 ml to maintain batter consistency.

How do I make the cake more chocolate-intense?
Add 1 tsp espresso powder dissolved in the milk or increase cocoa by 10–15 g and slightly reduce flour to maintain batter thickness. Folding in 60–80 g chopped dark chocolate or chips also boosts chocolate pockets without altering bake time significantly.

Is one-bowl mixing adapted for layered cakes?
Yes. Bake in two shallower pans and reduce bake time by 6–10 minutes; monitor internal temperature. Ensure even layer thickness for stable stacking and use a light soak or thin ganache between layers to maintain moisture.

Can I make this dairy-free?
Substitute plant-based milk of similar weight (oat or soy for body) and use melted coconut oil or neutral oil. Use dairy-free chocolate for ganache; expect slightly different mouthfeel and bake characteristics, possibly requiring a 5–10% increase in liquid for absorption differences.

Why did my cake taste too sour?
Overly sour flavor usually comes from a very acidic starter or using it immediately after feeding when acids peak. Use starter at peak or slightly receding fermentation and consider reducing starter weight by 10–20 g to balance tang. Adding a teaspoon of vanilla and a pinch more sugar can also mute sharp acidity without altering structure.

How to adapt to different pan sizes?
For 9x13 inch pans increase by 1.5x the recipe and expect bake times to change; use a probe to target internal temperature rather than relying on time. For smaller loaf pans, reduce batter volume accordingly and check doneness earlier.