How to Make Banana & Coconut Cake with Sourdough Discard

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This soft and moist banana and coconut cake with a buttery crumb topping is the perfect way to use up your sourdough discard. If you bake sourdough bread, you know the routine—feeding your starter often leaves you with extra discard. Instead of tossing it, add it to this cake for a gentle tang and depth of flavor that balances beautifully with the sweetness of ripe bananas and the tropical notes of coconut. In this post, I’ll walk you through the recipe step by step, share storage tips, and answer some of the most common questions about baking with sourdough discard.

Why You’ll Love This Cake Recipe

This cake turns out wonderfully fluffy and moist thanks to the creaming of butter and sugar, along with the natural sweetness and softness of ripe bananas. The coconut crumb topping adds a golden, crunchy finish that’s as beautiful as it is delicious. Made entirely with real food ingredients, this dessert feels wholesome and nourishing. It is something you can feel good about sharing with your family.

Difference Between Banana Bread and Banana Cake

Banana bread is usually denser and less sweet, while banana cake is lighter, fluffier, and a touch more indulgent. In this recipe, I’ve kept the sugar moderate. However, the creamed butter gives the cake its soft, airy texture and rich flavor. Instead of the traditional frosting you’ll often see on banana cakes, I’ve topped mine with a buttery coconut crumb for a simple yet irresistible twist.

Tips for making this recipe

  • To make this cake more nutrient dense, you could replace up to half of the white flour with whole wheat flour. I did that once and no-one noticed the difference.
  • You can use frozen bananas for this recipe. Let them defrost fully before adding to batter.
  • Clabbered milk, kefir, or buttermilk will all work here, so use whichever you have on hand.
  • Instead of the crumb topping, you could make a buttercream or cream cheese frosting for this cake. The cake will have to be stored in the fridge if you do.
  • This cake can be made ahead of time and frozen, either as a whole or cut into slices.

Ingredients You’ll Need

For the cake

For the crumb topping

How to Make Sourdough Discard Banana & Coconut Cake

Step 1

First you need to make the crumb topping so it can chill in the fridge while you prepare the cake. To make it, combine the flour, sugar and shredded coconut in a bowl. Then add in the cubed cold butter.

Step 2

Using a pastry cutter or your hands mix in the butter until it resembles coarse crumbs. Place this mixture in the fridge for 10-15 minutes so it can chill while you mix the cake batter.

Step 3

Preheat your oven to 180°C/350°F. In a bowl, cream together the butter and sugar.

Step 4

Add the eggs and whisk them in well.

Step 5

With a fork, mash the bananas and then stir them into the cake batter.

Step 6

Next mix in the sourdough discard and the clabbered milk (or kefir).

Step 7

In a separate bowl, combine the flour, baking soda and salt, then add into the cake batter a few spoons at a time, stirring well after each addition. You want a smooth batter, without dry lumps of flour in it.

Step 8

Finally stir in the shredded coconut.

Step 9

Pour the cake batter into a well-greased round or rectangular cake pan and spread it evenly with the back of a spoon. I used an 10.5 inch pie dish because that’s what I had on hand, but anything of similar size will work (I give you some suggestions for the cake tin to use in the recipe card).

Step 10

Take the crumb topping mix out of the refrigerator and sprinkle it evenly over the surface of the cake. My little helper did this job for me!

Step 11

Place the cake in the preheated oven and bake for 25-30 minutes until risen and golden brown and a skewer inserted into the center comes out clean. Check on your cake after it’s been baking for about 20 minutes to make sure it is not getting too dark on top – if it is, cover the top of the cake gently with a piece of aluminium foil.

Step 12

Let the cake cool completely before slicing. If you’d like extra neat slices, you can even bake it a day ahead and refrigerate it overnight—chilled cakes are much easier to cut cleanly.

FAQ & Helpful Tips

The main reason is that if you don’t discard some of your sourdough starter before you feed it, you’ll soon end up with a gigantic amount of starter. Also, if you are feeding your starter to make some bread, you will usually have some starter left over, for example if I need 200 grams of starter for my sourdough sandwich loaf I will always make a little extra. This way over time I end up with some discard sitting in the fridge, waiting to be used up.

Sourdough discard is the part of your starter that you remove before feeding your starter. It usually won’t be as active as a freshly fed starter and you cannot be use it to raise bread. While discard is not active enough to raise bread, it can be added to a variety of baked goods where it is not used as a leavening agent, but only to add flavor.

The main reason I use sourdough discard is to reduce waste—I’d much rather bake it into something delicious than throw it away, especially when it comes from a whole wheat starter. From a culinary perspective, discard brings a gentle tang and a subtle depth of flavor that makes baked goods more interesting. And don’t worry—because you usually add it in small amounts, it won’t make your muffins, cakes, or waffles taste sour. Instead, it enhances the flavor in the best way.

For best results, only use discard that is no more than 14 days old. Discard older than that is not necessarily unsafe to consume, but it can become overly sour and affect the flavor of your baked goods in a negative way. It is good practice to add discard to baked goods in small amounts once a week or twice a month, so you don’t end up with really old (and unusable) discard sitting in your fridge.

The discard itself is as healthy as sourdough starter – they are both teeming with beneficial microbes. However, discard is usually added to recipes with quick leavening agents (yeast, baking powder or baking soda), so you don’t get the health benefits of long fermentation like you would in recipes that use sourdough starter as a leaven.

No, unless you make it with frosting instead of the crumb topping or unless you live in a humid climate. That said, I usually keep mine in the fridge if I want it to stay fresh for longer.

Whether you choose to store your cake on the counter or in the refrigerator, you should keep it in an airtight container – this will keep it fresh for longer and prevent it from drying out. If you don’t have an airtight container, you could place the cake on a plate and wrap with a plastic bag.

On the counter this cake will keep for up to 4 days if your kitchen is cool, and in the fridge for around 6 days. Make sure you store it in an airtight container, as mentioned above. This cake can also be frozen, either as a whole or cut into slices. Wrap it well before freezing.

Serving Suggestions

This cake is delicious served with some hot tea or coffee. If you like, you could serve it drizzled with some raw cream. In my opinion it is rich enough to be served just by itself!

More Delicious Dessert Recipes:

Easy Crustless Pumpkin Pie From Scratch

 Fluffy Sourdough Discard Scones

Sourdough Gingerbread Muffins

Warm and Rich Sourdough Pumpkin Muffins

I would love to hear if you liked this easy and delicious sourdough discard cake! Let me know in the comments or email me at marta@heritagemama.com with any comments or questions you may have. For updates about my newest recipes and tutorials, subscribe to my newsletter or follow me on Pinterest.

round cake dish with banana coconut discard cake with one slice cut out and a knife on the side

Banana and Coconut Sourdough Discard Cake with Crumb Topping

A moist and fluffy banana and coconut cake made with sourdough discard and topped with a buttery crumb.
Prep Time 15 minutes
Cook Time 25 minutes
Total Time 40 minutes
Serving Size 16

Equipment

  • 10.5 inch wide pie dish or similar (see notes)

Ingredients

For the cake

  • ½ cup butter, softened
  • 1 cup brown sugar or rapadura
  • 2 eggs
  • 1 cup ripe bananas, mashed (2 medium bananas)
  • ½ cup sourdough discard
  • ¼ cup clabbered milk or kefir
  • 1⅔ cups flour
  • 1 tsp baking soda
  • 1 tsp unrefined salt
  • ½ cup shredded coconut

For the crumb topping

  • ¼ cup flour
  • ¼ cup shredded coconut
  • 2 tbsp brown sugar
  • ⅛ cup cold butter, cubed

Instructions

  • First you need to make the crumb topping so it can chill in the fridge while you prepare the cake. To make it, combine the flour, sugar and coconut in a bowl. Then add in the cubed cold butter.
  • Using a pastry cutter or just your own hands mix in the butter until it resembles coarse crumbs. Place this mixture in the fridge for 10-15 minutes so it can chill while you mix the cake batter.
  • Preheat your oven to 180°C/350°F. In a bowl, cream together the butter and sugar.
  • Add the eggs and whisk them in well.
  • With a fork, mash the bananas and then stir them into the cake batter.
  • Mix in the sourdough discard and the clabbered milk (or kefir).
  • In a separate bowl, combine the flour, baking soda and salt, then add into the cake batter a few spoons at a time, stirring well after each addition.
  • Finally stir in the shredded coconut.
  • Pour the cake batter into a well-greased round or rectangular cake pan and spread it evenly with the back of a spoon. I used an 10.5 inch round pie pan because that's what I had on hand, but anything of similar size will work (see notes below).
  • Take the crumb topping mix out of the refrigerator and sprinkle it evenly over the surface of the cake.
  • Place the cake in the preheated oven and bake for 25-30 minutes until risen and golden brown and a skewer inserted into the center comes out clean. Check on your cake after it's been baking for about 20 minutes to make sure it is not getting too dark on top – if it is, cover the top of the cake gently with a piece of aluminium foil.
  • Be sure to let the cake cool completely before slicing. If you’d like extra neat slices, you can even bake it a day ahead and refrigerate it overnight—chilled cakes are much easier to cut cleanly.
  • Serve it on its own or drizzled with some thick raw cream, with a nice hot cup of tea or coffee.

Notes

For the cake you can use any of the following:
10.5 inch round pie dish
9×13 inch rectangular cake pan
8 inch wide deep cake pan
Anything similar to these will work too! You could even use two regular loaf pans or one large one to bake this cake.

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