Plum Cake (German Zwetschgenkuchen)

german-zwetschgenkuchen From the southern region of Swabia, this popular German plum cake features a delicious yeast crust and butter streusel topping. While plums can be found in stores throughout the year, in celebration of plum season I want to share a traditional German plum cake with you. Depending on which region of Germany you're in, it's called Zwetschgenkuchen, Zwetschgendatschi, Quetschekuche or Pflaumenkuchen. Variations exist throughout Germany where some versions are made with a shortcrust pastry versus a yeast dough, some have streusel and some do not, some are round and some are rectangular. But they all celebrate the plump, juicy, sweet European plum, also known as Italian plums. Augsburg, a city in Bavaria northwest of Munich and one of the oldest cities in Germany, claims to have invented the original German plum cake, which they call Zwetschgendatschi. It's the city's signature dish. While variations exist even within Augsburg, the original version is made with shortcrust pastry and without any streusel.

The version we're making today is my personal favourite and is typical of the area I'm from of Stuttgart in Baden-Württemberg. It's made with yeast dough and sprinkled with streusel and it can be found throughout Germany. Zwetschgenkuchen typically calls for Italian plums (aka, European plums) and they are the variety most ideal for cooking not only because of their texture but also because their flavour becomes more complex through cooking. Italian plum season is short, usually from September through early October. This type of Zwetschgenkuchen, as with the Augsburger style plum cake, is typically made on a Backblech (a baking sheet) versus in a springform, though many round versions exist as well.

Cake:
3 lbs Italian plums, cut into qters, pits removed
1 cup warm milk, start with ¾ and add extra to the dough as needed
1½ Tbsp. dry active yeast
4 cups all-purpose flour, unbleached
¾ cup Monk Fruit Sweetener with Erythritol (Granular)
½ tsp. sea salt
1 stick butter, ½ cup melted, but not hot
2 eggs
1 tsp. pure vanilla extract

Streusel:
1 cup all-purpose flour, unbleached
1 cup Monk Fruit Sweetener with Erythritol (Granular)
1 tsp. ground cinnamon
½ cup butter, at room temperature

Dissolve the yeast into the ¾ cup warm milk and let is sit for 5-10 minutes until frothy.

Place the flour, sugar and salt in the bowl of a stand mixer and pour in the yeast mixture, melted warm (not hot) butter, eggs and vanilla extract. Give it an initial stir to combine the ingredients and then attach a dough hook and knead it on the bread setting ("2") for 4-5 minutes, adding the remaining ¼ cup milk as necessary. (The dough will be sticky but should hold together fairly well. It will not be firm enough to knead into a ball, think of it more as a thick batter.) Cover it loosely with plastic wrap and set it in a warm, draft free place to rise for an hour or until about doubled in size.

Preheat an oven to 350°F (180°C/160°C fan, Gas Mark 4). Place a rack in the middle of the oven. Generously butter a German Backblech extended to full length or a large jelly roll pan (at least 18" in length and 1" sides but even then the crust will be thicker than with the Backblech).

Use your hands to spread the dough out across the full length of the pan, pressing it up against the sides. (It's yeast dough so it will resist, but just keep pushing it back into position the best you can. Once you put the plums on it, those will help keep it in place.) Lay the plums close together in rows over the whole length of the dough on the sheet pan. (If you want your cake a bit sweeter you can sprinkle it *lightly* with sugar or cinnamon-sugar if you prefer more cinnamon. I emphasize "lightly" because the more sugar you add the more watery the cake will be as the sugar liquifies during baking and your streusel will also "melt" in contact with it.)

Set the pan in a warm place and let it rise for up to another hour.

To make the streusel: Place all the ingredients in a medium-sized bowl and use your fingers to bring it all together. Work with the mixture until it's thoroughly combined and forms a rough sand and clumpy texture. Sprinkle the streusel over the top of the cake.

Bake for 30-35 minutes or until the top is golden.

Let the cake sit for at least 10 minutes before slicing to let some of the liquid set. Slice the cake into squares and serve.

Cook's Notes: This cake holds up well for a day or two and is even more flavourful once the juices have absorbed into the dough.