from our cocoa kitchen · SURFSTR
Donauwelle with Cherries and SURFSTR Cocoa
Vanilla and cocoa cake ripple around sour cherries beneath a smooth vanilla buttercream and a thin chocolate topping. This classic German sheet cake cuts neatly after a thorough chill.
- Active preparation
- 50 min
- Cooking / baking
- 35 min
- Resting / chilling
- 215 min
- Total time
- 300 min
24 pieces from one 30 × 40 cm tray
Editorial recipe adaptation. Not yet kitchen-tested. Check ingredient labels for allergens.
02 / bring it together
let’s make it.
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Cook the vanilla pudding
Mix 40 g cornflour, 70 g sugar and 100 g of the pudding milk until smooth. Bring the remaining 400 g milk to a simmer. Whisk in the slurry and cook at a gentle bubble for 1 minute, stirring. Remove from the heat and stir in 5 g vanilla. Transfer to a bowl; press food-safe film directly onto the surface immediately.
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Prepare the tray and cream the butter
Heat the oven to 180 °C conventional or 160 °C fan. Line a 30 × 40 cm tray, at least 3 cm deep, with baking paper. Drain and pat the cherries dry. Beat 250 g soft butter with 220 g sugar, 5 g vanilla and the salt for 3–5 minutes. Beat in the eggs one at a time, scraping the bowl.
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Make two batters
Sift the flour and baking powder together. Mix briefly into the butter mixture, alternating with 75 g milk. Spread half the batter in the tray. Sift the cocoa into the remaining batter and stir in the remaining 30 g milk. Stop once smooth; do not keep beating after adding the flour.
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Layer the batter and cherries
Spread the cocoa batter gently over the pale layer. Distribute the 700 g drained cherries evenly and press them lightly into the batter. Do not stir the two colours together: the sinking cherries create the characteristic waves during baking.
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Bake and cool the base
Bake on the middle shelf for 25–35 minutes. Check from 25 minutes; a skewer inserted between the cherries should come out without wet batter. Leave the base in the tray on a rack until completely cool, about 60 minutes. Do not put buttercream on a warm cake.
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Match the pudding and butter temperatures
Let the covered pudding cool to about 20–22 °C. Keep its film touching the surface to prevent a skin. The 250 g butter for the cream should be soft and at the same temperature. Whisk the pudding smooth before combining; neither component should be fridge-cold or warm.
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Whip the buttercream
Beat the 250 g soft butter for 4–5 minutes until pale and fluffy. Beat in the cooled pudding one spoonful at a time at medium speed. Scrape the bowl and beat briefly until smooth. Slow additions and matching temperatures help the mixture stay emulsified.
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Spread and chill
Spread the buttercream evenly over the cold cake, right to the edges. Level with an offset spatula. Refrigerate for at least 90 minutes until the cream feels firm. Keep the cake level so the chocolate topping will have an even thickness.
-
Add a thin chocolate topping
Melt the chopped dark chocolate with 15 g refined coconut oil in a dry bowl over barely simmering water; the bowl must not touch the water. Remove and stir until smooth. Cool until just lukewarm, about 30–32 °C, then spread quickly in a thin layer over the chilled buttercream.
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Draw waves and slice
As the topping begins to thicken but is still soft, draw parallel waves with a fork. Chill for about 60 minutes until set. Let the cake stand for 10 minutes before cutting into 24 pieces with a warm, dry knife; wipe and warm the blade between cuts.
The recipe in pictures
03 / the numbers
nutrition, clearly.
Calculated estimates, not laboratory measurements. Any per-100-g values use the stated estimated finished weight.
| Nutrition estimates | Per slice |
|---|---|
| Energy | 1485 kJ / 355 kcal |
| Fat | 23.3 g |
| of which saturates | 14.2 g |
| Carbohydrate | 30.5 g |
| of which sugars | 18.4 g |
| Fibre | 1.9 g |
| Protein | 4.7 g |
| Salt | 0.21 g |
Per slice; calculated from ingredients. Product labels and slice sizes vary.
Tips and storage
Keep the waves clear
Weigh the cherries after draining and blot away surface juice. Excess juice can leave wet pockets in the cake. Add them over the dark batter without mixing the layers.
Rescue a split cream
If the cream looks curdled because it is too cold, warm the outside of the bowl briefly over lukewarm water while mixing. If it is loose and greasy because it is too warm, chill for 10 minutes and beat again. Avoid adding more liquid.
A topping that slices cleanly
The small amount of coconut oil softens the chocolate coating. A warm, dry knife and a short rest outside the fridge help keep it from cracking. Refined coconut oil adds less coconut flavour.
An optional coffee accent
For a separate variation, dissolve 2 g instant espresso in the 30 g milk for the cocoa batter. Keep the total milk unchanged. The classic version above contains no coffee.
Storage
Keep covered in the fridge at 4 °C or below for up to 3 days. Freeze individual portions for up to 1 month and thaw overnight in the fridge. The topping may lose some shine after freezing.
SURFSTR · DUTCH PROCESS
it starts with cocoa.
SURFSTR Dutch-process cocoa contains 20–22% cocoa butter. Use the cocoa specified in the recipe: natural cocoa is not always a direct substitute.
Meet the cocoa