These sourdough banana bread cookies take everything good about banana bread and get it into cookie form properly: ripe banana, brown sugar, a real hit of cinnamon, then toasted walnuts and chocolate chips folded through. They hold a proper cookie shape too, chewy at the edges and soft in the middle!
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This started as my Chocolate Chipless Sourdough Cookies (Chewy Sugar Cookies) base, reworked because I had one very ripe banana on the counter and knew that if I turned it into sourdough banana bread, I'd be eating the whole loaf myself. Seb isn't remotely bothered by banana bread, but put a cookie in front of him and he's straight back for a second one. It took four or five batches to get the ratio right, but it's there now. Banana in a cookie is trickier than it sounds.
Recipe Highlights
TASTE: ripe banana, brown sugar, toasted walnut, warm cinnamon and subtle, barely-there sourdough tang in the background
TEXTURE: crisp edges, soft chewy centre
WHAT'S SPECIAL: chewy, not cakey
SEB'S RATING: asked why I don't just make these instead of banana bread
Ingredient Notes
- Banana: weigh it after peeling rather than trusting "one banana", since sizes vary enough to throw the whole ratio off. You want 70g of mashed fruit, and it should be properly ripe, well spotted or even mostly black (= concentrated flavour). Too much banana and the cookies spread and turn cakey instead of chewy.
- Browned butter: browning rather than just melting it toasts the milk solids and gives you a nutty, faintly caramelised depth that plain melted butter can't. It also allows for some extra moisture to evaporate, allowing for more banana and water from discard.
- Sourdough discard: unfed, 100% hydration discard straight from the fridge is exactly what you want. If you're still working out what discard actually is and what else you can do with it, my Sourdough Discard 101 guide covers the basics.
- Walnuts: toast them in a dry pan for a couple of minutes before chopping if you want more flavour and crunch out of them. Chopped rather than left whole so they distribute evenly through the dough instead of leaving you with the occasional giant piece.
- Chocolate chips: If you want to lean fully into the walnut angle, leave them out and you'll still get a properly good cookie.
Find the full ingredient quantities and instructions in the recipe card below.
Step-by-Step Method
1. Brown the Butter. Melt the butter in a light-coloured pan over medium heat, swirling occasionally. It'll foam, then turn golden and smell nutty, about 4 to 5 minutes. Pour it into a heatproof bowl straight away to stop it cooking further, and let it cool until just warm.
2. Make the Dough. Beat the granulated sugar and brown sugar into the browned butter for 2 minutes, until glossy. Add the egg yolk and beat for a further 2 minutes, until noticeably thickened and paler. Mix in the mashed banana until just combined; it won't emulsify as smoothly as the butter and egg did, and a slightly broken, streaky look at this stage is completely normal, not a sign anything's wrong. Fold in the sourdough discard with a balloon whisk or spatula, using a light hand.
3. Add the Dry Ingredients. Whisk together the flour, bicarbonate of soda, cinnamon and salt in a separate bowl. Add this to the wet mixture and stir until just combined, with no dry streaks left. Don't overmix here, once the flour's in, more mixing develops gluten you don't want, and the cookies turn tough instead of chewy. Fold in the chopped walnuts and chocolate chips.
4. Chill the Dough. Cover and chill for at least 4 hours, ideally overnight. This dough is wetter and softer than a standard sugar cookie dough because of the banana, so don't shortcut the chill. It needs the time to firm up, or the cookies will spread thin in the oven.
5. Shape. Preheat the oven to 180°C (350°F) and line a tray with parchment. Divide the dough into 9 to 10 portions of about 76-80g each and roll into balls. If your kitchen runs warm, freeze the shaped balls for 15 to 20 minutes before baking to help control spread.
6. Bake. Space them well apart on the tray and bake for 18 to 19 minutes, until the edges are set and golden but the centres still look slightly underdone. Leave them on the tray for 10 minutes before moving to a wire rack; they'll keep firming up as they cool.
Tips
⚖️ Weigh the banana, don't eyeball it. This dough is balanced precisely around 70g of mashed fruit, and bananas vary too much in size to trust "half a banana" as a measurement.
🍌 Use the ripest banana you've got. Well spotted or mostly black gives you more concentrated banana flavour without adding more moisture than the recipe is built for.
❄️ Freeze the shaped dough balls for 15 to 20 minutes if your kitchen is warm. It buys you extra insurance against spreading on top of the chill, particularly useful in summer.
🔥 Toast the walnuts. A couple of minutes in a dry pan brings out more depth than raw walnuts folded straight in.
🥄 Stop mixing the moment the flour disappears. Overmixing at this stage is the single most common reason these turn out tough rather than chewy.
RECIPE FAQs
Well spotted at minimum, and mostly black is even better. A very ripe banana gives you more concentrated flavour for the same weight, which matters here since the recipe is built around a specific 70g measurement. If your banana isn't ripe enough, roast it whole at 150°C for 15 to 20 minutes until the skin blackens, then let it cool before mashing.
This almost always comes down to too much banana. Weigh it after peeling rather than estimating, and stick to 70g. Underripe banana is another culprit. Overmixing once the flour goes in is yet another common culprit, since it develops gluten that makes the crumb denser and softer rather than chewy.
Yes, active starter works fine here. The bicarbonate of soda is doing the leavening, so you're not losing any rise by using discard instead. Active starter will give slightly less sourdough tang, which some people prefer.
Both freeze well. Portion the raw dough into balls before freezing and bake straight from frozen, adding 2 to 3 minutes to the time. Baked cookies freeze for up to 3 months, just let them come back to room temperature before eating.
Yes, this dough is wetter than my other sourdough cookie doughs because of the banana, and that's expected.
Serving Suggestions
These are better slightly warm than fully cooled, more so than the plain sourdough sugar cookie base they came from. Give them 10 minutes out of the oven and the chocolate chips are still soft enough to pull, which suits an afternoon coffee far better than a colder cookie does.
If you're eating them the next day, a few seconds in the microwave brings that back.
Storage
Baked cookies keep in an airtight container at room temperature for up to 3 days, but they do lose their crispy edges and generally tend to go a little "wet". Thanks, banana!
For longer storage, freeze the baked cookies for up to 3 months and let them come back to room temperature before eating. The raw dough freezes well too, portion it into balls first, then bake straight from frozen, adding 2 to 3 minutes to the time. Don't freeze the mashed banana on its own and add it later, it separates and throws off the texture.
More Sourdough Cookies to Try
If walnuts and banana bread flavours are your thing, my Sourdough Discard Chocolate Chip Cookies are the closest sibling to these, built from the same chewy base without the fruit. The Matcha Sourdough Cookies with White Chocolate Chips take the same mix-in-forward approach in a completely different direction, and the Sourdough Peanut Butter Cookies share the same soft, chewy texture if that's what you're after. There're more ideas in my sourdough dessert recipes collection if you want to keep browsing:
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Sourdough Banana Bread Cookies with Walnuts and Chocolate Chips
Equipment
- Small saucepan, light-coloured (for browning the butter)
- Balloon Whisk
- Digital Kitchen Scales
- Cooling Rack
Ingredients
- 100 g unsalted butter browned and cooled until just warm
- 60 g granulated sugar
- 90 g soft light brown sugar
- 1 large egg yolk
- 70 g very ripe banana mashed (weigh it after peeling)
- 80 g sourdough discard 100% hydration
- 210 g all-purpose flour (plain flour)
- ½ teaspoon baking soda (bicarbonate of soda)
- 1 teaspoon ground cinnamon
- ¼ teaspoon fine salt
- 70 g walnuts roughly chopped
- 100 g chocolate chips milk or dark
Instructions
- Melt the butter in a light-coloured pan over medium heat, swirling occasionally, until it foams, then turns golden and smells nutty, about 4-5 minutes. Pour into a heatproof bowl straight away to stop it cooking further, and set aside to cool until just warm.
- Add the granulated sugar and brown sugar to the browned butter and beat with an electric mixer for 2 minutes, until glossy and combined.
- Add the egg yolk and beat for a further 2 minutes, until noticeably thickened and paler.
- Mix in the mashed banana until just combined. It won't emulsify as smoothly as the butter and egg did, a slightly broken, streaky look at this stage is normal.
- Fold in the sourdough discard with a balloon whisk or spatula, using a light hand.
- In a separate bowl, whisk together the flour, bicarbonate of soda, cinnamon and salt.
- Add the dry ingredients to the wet mixture and stir until just combined, no dry streaks remaining. Don't overmix here or the cookies will turn tough rather than chewy.
- Fold in the chopped walnuts and chocolate chips.
- Cover the bowl and chill the dough for at least 4 hours. This dough is softer and wetter than a plain sugar cookie dough, so don't shortcut the chilling time.
- Once chilled, preheat the oven to 180°C (350°F) and line a baking tray with parchment paper.
- Divide the dough into 10 portions (about 76-78g each) and roll into balls. If your kitchen is warm, freeze the shaped balls for 15-20 minutes before baking to help control spread.
- Space the dough balls well apart on the tray and bake for 18-19 minutes, until the edges are set and golden but the centres still look slightly underdone. As soon as they come out of the oven, drop the tray from 20cm height - this will create a crackly top on the cookies.
- Leave the cookies to cool on the tray for 10 minutes; they'll continue to firm up as they cool, then transfer to a wire rack. Best served on the day they are made, as they lose crispiness over time.
Notes
Nutrition
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