In my childhood, wild (or forest) blueberries used to be frequently around during the season. Actually, they were the type of berry that I knew as blueberry for a large part of my growing up before cultivated blueberries started taking over and eventually ruled supermarket shelves and market stalls. Delicious as the latter ones may be, forest blueberries are now are rarity and seldom available, and I am fearful that this taste of my childhood may one day be entirely lost. Still some market stalls carry small baskets in the summer months and I then never fail to indulge.
Their dry and sour/discretely sweet taste, intense dark-blue color and juice makes forest blueberries distinctly different from cultivated blueberries. They are a great ingredient to baking given that their slight acidity combines fantastically with sweeter fillings and crusts. Certainly, with their rich and almost indigo color they also look fantastic in or on any cake.
The recipe below gives center stage to the tiny fruit which is also referred to as the „blue gold from the forest “ in Germany. Apart from a discrete vanilla flavoring, violet syrup adds a fragrant background taste. All else it takes is a truly buttery crust. 🙂
For the dough:
- 500 grams of cake flour (German type 405)
- 200 grams of finely granulated sugar
- 1 heaped teaspoon of baking powder
- 1/2 teaspoon of salt
- 285 grams of soft butter
- 2 eggs
- some drops of vanilla extract or seeds of 1 vanilla pod
For the filling:
- 500 grams of wild blueberries
- 1 heaped tablespoon of vanilla sugar
- 2 tablespoons of Maïzena
- 2 to 3 tablespoons of water
- 1 to 2 tablespoons of violet syrup
For the egg wash:
- 1 egg yolk
- 1 teaspoon of icing sugar
Preparing the dough:
- Pass the four through a fine mesh into a large bowl. Add the sugar, baking powder and salt.
- With an electric mixer (kneading hooks), work in the butter, eggs and the vanilla extract. When the ingredients are roughly mixed, transfer onto a working surface and knead well until smooth.
- Form a ball, wrap into cellophane and leave in the fridge for at least 2 hours, ideally overnight.
Preparing the filling:
- Wash the blueberries and put into a saucepan.
- In a small bowl, mix the Maïzena, vanilla sugar and water. Pour the mixture over the blueberries and warm up on medium heat. Add the violet syrup.
- Let simmer for a few minutes until the filling thickens (approximately 5 minutes). Note that the filling should be relatively thick or too much liquid would seep into the dough and the tart would not stay together.
- Let cool down completely. It can be kept in the fridge overnight if prepared together with the dough.
Putting the cake together:
- The dough and the filling need to be taken out of the fridge at least 2 hours before processing. Knead the dough through strongly once again before putting the cake together.
- Butter a Ø 28 cm cake pan with a smooth rim.
- Pre-heat the oven to 170 degrees Celsius.
- Roll out approximately 1/3 of the dough and cut out the Ø 28 cm top layer. (To make handling easier, place the cut out layer in the fridge for 20 minutes before continuing.)
- Press the remainder of the dough into the bottom of the pan and form ca. 0.5 to 1 cm high sides.
- Spread the filling over the dough, then place the top layer on top and gently press together the edges.
- For the egg wash, whisk the egg yolk and the icing sugar, then brush onto the top of the cake.
- Bake for 45 minutes at 170 degrees Celsius. The cake should by then have adopted a nice golden-brown color. Reduce the temperature to 150 degrees Celsius and continue baking for another 15 minutes. Turn off the oven an leave in the heat for another 15 to 20 minutes.
- Let cool down completely before serving.
- Optionally, drizzle with a few drops of violet syrup before serving.