Healthy German Plum Sheet Cake with Greek Yogurt

The aroma of cinnamon and baking plums filling the air as you walk inside is simply wonderful. Once, while baking this for a friend from Bavaria, I used plums that were far too large and watery, resulting in a purple puddle in my oven.

It was a complete mess, but it taught me that selecting the correct fruit is absolutely vital for this recipe.

This version of the German Plum Sheet Cake avoids heavy amounts of refined sugar, utilizing Greek yogurt instead for a lighter result. It’s a great alternative that provides an authentic, tart profile without the sugar crash typical of old-school bakery cakes.

You can expect a cake that is slightly tangy, naturally sweet, and structurally sound. The aim is a base as light as a cloud paired with jammy, concentrated fruit. This treat tastes fantastic whether it's served slightly warm or at room temperature.

German Plum Sheet Cake: A Simple Bake

Greek Yogurt: The acidity breaks down gluten proteins, which ensures the cake stays tender instead of becoming bread like.

Cornstarch Barrier: A thin layer of starch absorbs the excess juice the plums release during baking. This stops the bottom from getting soggy.

If you want an even finer texture, you can follow this cake flour guide to swap out the all purpose flour.

What You'll Need to Bake

You don't need a mountain of gear for this. A standard 12x17 inch rimmed baking sheet is the gold standard here. I always use parchment paper because trying to scrub baked on sugar and plum juice off a pan is a nightmare I wouldn't wish on anyone.

For mixing, a large bowl and a sturdy spatula do the trick. If you have a hand mixer, it helps with the creaming process, but a whisk and some elbow grease work just fine. Just make sure your eggs are at room temperature so the batter doesn't curdle when you mix them in.

The Right Ingredients for Plums

The stars here are the Italian Prune Plums. They are smaller, oval, and way more tart than the big round ones you see in most supermarkets. If you can't find them, look for any plum that feels firm and has a deep purple skin.

Coconut sugar gives the base a slight caramel note that pairs well with the cinnamon. Greek yogurt replaces a chunk of the butter, which lightens the whole feel of the slice. Cornstarch is the unsung hero that manages the moisture.

The Quick Breakdown

Shopping List Breakdown

• 1.5 cups (190g) All purpose flour Why this? Provides the structure for the base (Substitute: Spelt flour)
• 0.5 cup (100g) Coconut sugar Why this? Lower glycemic index and caramel flavor (Substitute: Brown sugar)
• 0.5 cup (120g) Plain Greek yogurt Why this? Adds moisture and acidity for lift (Substitute: Sour cream)
• 0.25 cup (55g) Unsalted butter, melted and cooled Why this? Richness without being heavy (Substitute: Coconut oil)
• 2 Large eggs, room temperature Why this? Binds the batter and adds lift (Substitute: Flax eggs)
• 1 tsp (5ml) Vanilla extract Why this? Rounds out the tart fruit (Substitute: Almond extract)
• 1.5 tsp (7g) Baking powder Why this? Essential for the rise (Substitute: Baking soda + cream of tartar)
• 0.25 tsp (1.5g) Salt Why this? Balances the sweetness (Substitute: Sea salt)
• 2 lbs (900g) Italian Prune Plums, pitted and quartered Why this? High pectin and tart flavor (Substitute: Damson plums)
• 1 tbsp (15ml) Melted butter Why this? Keeps plums from sticking (Substitute: Melted coconut oil)
• 1 tbsp (8g) Cornstarch Why this? Absorbs fruit juices (Substitute: Arrowroot powder)
• 1 tsp (2g) Ground cinnamon Why this? Classic autumn warmth (Substitute: Nutmeg)
• 2 tbsp (25g) Coconut sugar Why this? Caramelizes the fruit tops (Substitute: Turbinado sugar)

Putting the Cake Together

Phase 1: Assembling the Base

1. Set your oven to 350°F (175°C) and prepare a baking sheet with a layer of parchment paper.
2. In a large mixing bowl, blend the melted butter and coconut sugar until they are well incorporated.
3. Incorporate the eggs one at a time, then stir in the vanilla extract and Greek yogurt until the batter is smooth and creamy. Note: Using room temperature eggs prevents the mixture from separating.
4. Combine the flour, salt, and baking powder, then gently fold these dry ingredients into the wet batter with a spatula. Be careful not to overmix.
5. Distribute the batter evenly across the lined sheet pan.
6. Sprinkle a light coating of cornstarch over the surface of the batter. Note: This acts as a moisture barrier.

Phase 2: Layering the Fruit

7. Mix the quartered plums with cinnamon, 1 tbsp melted butter, and 2 tbsp coconut sugar.
8. Arrange the plums in close, overlapping rows on top of the German Plum Sheet Cake batter. Press them in lightly, ensuring they don't sink to the bottom.

Phase 3: The Bake

9. Bake for 55 minutes until the edges are golden brown and the plums are bubbling and releasing their juices.
10. Allow the cake to cool in the pan for 15 minutes before cutting it into 16 squares.

Avoiding Common Baking Blunders

If the cake feels too wet, it usually comes down to the fruit. Italian Prune Plums have a specific balance of water and pectin. Globe plums are basically water balloons, and they'll swamp your batter. Always pat your sliced fruit dry with a paper towel if they look overly juicy.

Another issue is the mixing. If you stir the flour in too aggressively, you develop too much gluten. This turns your German Plum Sheet Cake from a tender dessert into something that feels more like a dense focaccia. Use a folding motion, not a stirring motion.

Fixing a Soggy Bottom

This happens when the fruit juices penetrate the batter. Make sure your cornstarch layer is even and that you aren't overloading the pan with too much fruit.

Avoiding a Dense Base

If the cake didn't rise, your baking powder might be old. Check the expiration date or do the "bubble test" in hot water to ensure it's still active.

Ensuring Even Baking

Use a light colored sheet pan. Dark pans absorb more heat and can burn the bottom of your German Plum Sheet Cake before the center is set.

Adjusting the Batch Size

If you're just baking for two, you can halve this recipe. Use a 9x13 inch pan or a smaller baking sheet. I recommend beating one egg in a small bowl and using half of it to keep the ratios exact. Reduce the baking time by about 20%, but start checking at 40 minutes.

For a larger party, doubling the recipe works, but don't bake it all in one giant deep pan. Stick to two separate sheet pans. If you try to make it too thick, the center won't cook through before the edges burn.

Keep the temperature at 350°F (175°C) and bake them on different racks, swapping them halfway through.

Debunking Cake Myths

You might hear that you need to sift flour for a sheet cake. Honestly, for this recipe, a good whisk is enough to break up lumps. Sifting is great for sponges, but this base is heartier.

Some people think you have to peel the plums. Don't do that. The skins provide the structure that keeps the fruit from disintegrating into a jam, and they add a nice pop of color to the German Plum Sheet Cake.

Keeping Your Cake Fresh

Store any leftover slices in a sealed container in the cooler for up to 3 days. I find that the flavors actually deepen after a night in the fridge. To get that fresh baked feel back, pop a slice in the toaster oven for 3 minutes.

You can also freeze this cake. Wrap individual slices in parchment paper and then foil. Store them in a freezer bag for about 2 months. Thaw them in the fridge overnight or microwave for 30 seconds for a quick treat.

For zero waste, if you have leftover plum scraps or bruised fruit, simmer them with a bit of sugar and lemon juice to make a quick plum compote. This is great on top of porridge or yogurt for breakfast.

Ways to Twist the Recipe

Sliced pears or tart apples are wonderful substitutes if you don't have plums. Simply toss them in the same cinnamon sugar mixture. I recommend adding a pinch of nutmeg to the base if you choose apples.

To add a bit of crunch, top the cake with a cinnamon streusel. Combine 0.5 cup flour, 0.25 cup cold butter, and 0.25 cup sugar until crumbly, then sprinkle this over the plums before baking. For a more indulgent option, try my chocolate cupcakes.

For a Vegan Friendly Version

Substitute the eggs with flax eggs (1 tbsp ground flax + 3 tbsp water per egg) and use a plant based butter. You can also swap the Greek yogurt for a thick soy or cashew yogurt.

For a gluten-free Experience

Use a gluten-free flour blend containing xanthan gum. The texture will be a bit more delicate, so allow the German Plum Sheet Cake to cool completely before slicing.

What to Serve Beside It

This cake is a quintessential "Kaffee und Kuchen" (coffee and cake) treat. A bold espresso or a strong black coffee balances the sweetness of the coconut sugar and highlights the tartness of the plums.

If you prefer tea, a fragrant Earl Grey or a soothing chamomile are wonderful pairings. For a more indulgent afternoon, serve a warm slice with a dollop of lightly sweetened whipped cream or some vanilla ice cream.

I truly believe that the simpler the pairing, the better. This German Plum Sheet Cake relies on the harmony between the fruit and the crumb, so avoid heavy additions that could overpower those flavors.