Sourdough Apple Donut Cake

By Amanda Paa – Updated September 12, 2024
5 from 5 votes
This moist and flavorful apple snack cake is made with sourdough discard and tastes just like an apple donut! The apples are thinly sliced so they disappear into the soft and fluffy crumb, and the cinnamon sugar topping bakes into a papery thin, crackly crust. Each piece is pure fall delight. So easy to make, no mixer needed.
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sourdough apple cake on a blue plate with a gold fork

Why You’ll Love This Sourdough Apple Cake

I am the snacking cake type rather than the layer cake type. They’re great eaten cold from the fridge, while you’re running out the door. And they can pass as breakfast, especially when they have donut in the title.

This Sourdough Apple Donut Cake is ready to charm all of your fall loving hearts, sending scents of apples, brown sugar, and cinnamon throughout your house. It has all the flavors of a warm, soft apple donut and a crisp, crackly cinnamon sugar top (!!) that is the perfect compliment. Eaten warm with a little salted butter is a dream. This cake is incredibly simple to make, no stand mixer needed, and can be in the oven with less than 20 minutes of prep time.

sourdough apple cake cut into slices

Using Thinly Sliced Apples Rather Than Diced Apples:

Most apple cakes use diced apples, which can be a little awkward and heavy, but here I’ve used finely sliced apples slices so they nearly disappear into the crumb. This gives the cake apple flavor in every bite. To make the paper thin slices I use a mandoline, then run my knife through them once more.

I learned this smart technique from Pinch of Yum’s Cinnamon Sugar Apple Cake, which inspired this recipe – it looked so delicious and cozy! And I thought it would be fun to bring a sourdough element to it and give you a fall sourdough snack cake as a follow up to my Sourdough Discard Rhubarb Cake for spring.

Recipe Testing Notes:

Using Lindsay’s recipe as a starting, I knew I wanted this to be a smaller cake in an 8×8 inch cake pan, as it’s just two of us here. From there, it was a bit of a challenge to get the moisture level right while incorporating the sourdough discard and a whole egg. To make up for that, I pulled back on the milk and flour. The first 3 tests were all a bit heavy from too much apple. I wanted it to be more light and fluffy, yet still be apple forward.

It also needed a bit less sugar and more salt than I assumed, the later I find to be the case when developing any type of sourdough discard recipe. I’m not sure why that is, but I’m guessing the acids in the starter neutralize the salt more? Baking powder resulted in a fluffier crumb, rather than baking soda. And a few more tests later, we got there!

What does sourdough discard do for cakes?

Sourdough discard doesn’t make cakes taste sour. Instead, it makes them fluffy and soft because it increases the acidity of the cake batter, which weakens the gluten in flour. And because it has already been fermented, the gluten in the sourdough discard itself has also been weakened. It has the same effect in this fabulous Sourdough Discard Pumpkin Bread and my Blueberry Sourdough Muffins!

The other thing discard does in baking is bring out the flavors of other ingredients in the recipe. This is due to the naturally occurring alcohols and acids that develop in sourdough starter, and both are flavor enhancers. That means the main components of this cake, apples and cinnamon, really shine.

baking ingredients in bowls
apple cake batter in a glass bowl
cake batter

How to Make An Amazing Sourdough Apple Cake:

  • Stir together milk and lemon juice, set aside. (This is a like a faux buttermilk.)
  • Use mandoline (or very sharp knife) to cut your apple wedges into paper thin slices. Then run your knife through them vertically to cut into sticks, then horizontally so the sticks are kind of like rectangles. This doesn’t have to be perfect, you’re just trying to make the pieces smaller.
  • To a large mixing bowl, add brown sugar, egg, and sourdough discard. Whisk together until homogenous. Add oil, milk mixture, and vanilla. Whisk again
  • To a small bowl, add flour, baking powder, salt, and nutmeg. Whisk.
  • Add flour mixture to wet ingredients, and use a spatula to stir until mostly combined, but they are still flour streaks left. Then add apples and fold in to distribute.
  • Scrape batter into a greased or parchment lined 8×8 baking pan (do not use glass). Use back of spoon to even out the batter. The mix topping ingredients together and evenly sprinkle over the cake. Bake!

What Type of Apples Are Best for Making a Cake?

In terms of sweetness level, I like to go with an apple that is somewhere in between on the sweet/tart spectrum. Then it’s important to use an apple variety that is crisp and holds its shape a bit. A few of my favorites that fall into this category include:

  • Cosmic Crisp (my favorite for baking and what I used in this recipe)
  • Honeycrisp
  • Sweet Tango
slices cut of an apple snacking cake
crumb photo of sourdough apple cake

How long is sourdough discard good for?

You can keep sourdough discard in your refrigerator for up to 10 days. The discard will be more sour the longer it stays in the fridge. So for something like this cake, sourdough chocolate chip cookies, or sourdough pumpkin bread, where I don’t want the sourness to come through, I use discard that is less than 5 days old.

Your discard might accumulate a little liquid on the top while it’s in the fridge, which is called hooch, simply meaning alcohol that is the byproduct of fermentation. You can simply pour the liquid off into garbage, then scrape the very top off, and use the rest as discard.

More Sourdough Discard Recipes:

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piece of sourdough apple cake on a pink backround

Sourdough Apple Donut Cake

This moist and flavorful apple cake is made with sourdough discard and tastes just like an apple donut! The apples are thinly sliced so they disappear into the soft and fluffy crumb, and the cinnamon sugar topping bakes into a papery thin, crackly crust. Each piece is pure fall delight. So easy to make, no mixer needed.
5 from 5 votes
Prep Time :18 minutes
Cook Time :35 minutes
Yield: 9 pieces
Author: Amanda Paa

Ingredients

  • 80 grams whole milk
  • 1 teaspoon lemon juice
  • 205 grams of quartered apple wedges
  • 130 grams brown sugar
  • 1 egg, room temperature
  • 70 grams sourdough discard, room temp preferred so that it is easy to incorporate
  • 40 grams sunflower or grapeseed oil
  • 3/4 teaspoon pure vanilla extract
  • 135 grams all purpose flour
  • 1 1/2 teaspoons baking powder
  • 1/2 teaspoon + 1/8 teaspoon fine sea salt
  • pinch of nutmeg
  • For topping: 3 tablespoons granulated sugar + 1/2 teaspoon ground cinnamon + pinch of salt

Instructions 

  • Preheat oven to 375 degrees F.
  • Stir together milk and lemon juice, set aside. (This is a like a faux buttermilk.)
  • Use mandoline (or very sharp knife) to cut your apple wedges into paper thin slices. Then run your knife through them vertically to cut into sticks, then horizontally so the sticks are kind of like rectangles. This doesn't have to be perfect, you're just trying to make the pieces smaller.
  • To a large mixing bowl, add brown sugar, egg, and sourdough discard. Whisk together until homogenous. Add oil, milk mixture, and vanilla. Whisk again to combine.
  • To a small bowl, add flour, baking powder, salt, and nutmeg. Whisk.
  • Add flour mixture to wet ingredients, and use a spatula to stir until about half combined. Then add apples and fold in to distribute, just until no flour streaks are left. Be sure to not overmix.
  • Scrape batter into a greased or parchment lined 8×8 baking pan (do not use glass). Use back of spoon to even out the batter. The mix topping ingredients together and evenly sprinkle over the cake.
  • Turn OVEN DOWN to 325 degrees F and bake for 35 to 38 minutes, until toothpick comes out with a few moist crumbs, but not wet. Let cool and serve.

Notes

*Recipe adapted from Pinch of Yum.
*An oven thermometer is always helpful to make sure your oven is actually the temperature it is reading. I always use one, as my oven runs hot. This can negatively impact your bake. 
*Do not decrease the amount of sugar in the topping; it is not too sweet and gives this cake the gorgeous and delicious crackly top. 

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September 12, 2024

COMMENT & RATE

I look forward to your comments, reviews and questions! If you love this recipe, please rate it when you leave a comment. Star ratings help people discover my recipes. Your support means a lot; thank you for being a part of the Heartbeet Kitchen community.

Amanda

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Recipe Rating




5 from 5 votes

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16 comments

  1. Sam

    Can this recipe be baked in muffin tins? Time to bake ? 20-25 min?

  2. Roney

    Would it be OK to use buttermilk in this recipe instead of the milk + lemon juice? p.s. Love your easy sourdough French toast recipe! Have made it a few times now :)

    • Amanda Paa

      Yes, it’s even better with actual buttermilk! I just don’t always have it on hand. And so glad you like the French toast. ❤️

  3. Lisa

    5 stars
    Definitely make again!
    Good, so moist and easy to make.

    • Amanda Paa

      Yay, thanks for making the recipe!

  4. Bettina

    5 stars
    This was so delicious. Lovely taste of fall and not too sweet. This will be on autumn/winter rotation, for sure.

    • Amanda Paa

      Yay, so glad you liked it! Thanks so much for making the recipe.

  5. Michelle Rickert

    Hi, this recipe looks amazing! I’m trying to avoid seed oils. Could I substitute butter?
    Thank you!

    • Amanda Paa

      Hi! The oil is one of the reasons the crumb is so fluffy. I’d use refined coconut oil instead (so coconut flavor doesn’t come through). Olive oil may work too, but it also may cover some of the apple flavor? Not sure.

  6. Joan Anderson

    Hi I emailed you yesterday about (what is sourdough discard) mean. Is it something I have to make up separately or is it the combination of the milk and lemon juice.Im just rely confused about this and would love to make. thanks

    • Amanda Paa

      Hi Joan! Sourdough discard is sourdough starter that is unfed, or inactive for making a loaf of bread rise. You’d need a sourdough starter to acquire it.

  7. Joan

    Im so sorry to bother you but I dont understand what sourdough discard means or is. I would love to make your sourdough apple cake.

  8. Nancy

    5 stars
    Again, why do you recommend not using a glass baking dish?

    • Amanda Paa

      Hello! Glass should not be used in baking cakes because they do not conduct heat well. Because glass is an insulator, rather than a conductor, it’s slow to heat but, once hot, retains that heat for longer. This can result in uneven baking: By the time the interior is baked through, the exterior is often overcooked, dry, or dark.

  9. Andrea

    5 stars
    I made this recipe and it was fantastic! Being plant based, I don’t consume eggs or dairy, so I substituted with flax egg and soy milk and it turned out delicious. Even my non-vegan friends loved this cake!

  10. Rachel

    5 stars
    This recipe was so easy and it turned out great! I had all the ingredients on hand (subbing almond milk for the milk which worked out fine), so I decided to do some fall baking this morning. The thin apple slices really do kind of disappear into the cake, making it moist. Make this and enjoy with hot coffee!