Burgenland Cookies

Ingredients

1 stick plus 3 tbsp150 gunsalted buttersoftened. German butter is unsalted and has about 82 percent fat. In the US use unsalted butter; European-style unsalted butter is closest. In the UK use unsalted butter.
½ cup plus 1 tbsp70 gpowdered sugarVery finely ground sugar for icings and dusting. In the US use powdered sugar (confectioners' sugar); in the UK, icing sugar.
1 pinchsalt
2 tspvanilla sugar1 packet = 2 tsp (8 g). Vanilla sugar is sugar flavored with vanillin (artificial vanilla), sold in small packets of about 8 g. In the US use 1 tsp vanilla extract plus 2 tsp sugar for each 8 g packet; in the UK, vanilla sugar sachets, or 1 tsp vanilla extract plus 2 tsp sugar per sachet.
2 cups250 gall-purpose flourIn German recipes plain flour means soft wheat flour Type 405 unless stated otherwise. In the US use all-purpose flour; in the UK, plain flour.
1 to 2egg yolks

1 ¾ oz50 gcouverture chocolateruby. Couverture is chocolate with a high cocoa butter content that melts smoothly for coating and glazing. In the US use good-quality baking chocolate bars or couverture wafers (not chocolate chips); in the UK, couverture chocolate or a good-quality cooking chocolate bar.
2 tbsp30 mlheavy creamGerman cream for whipping has about 30 to 32 percent fat. In the US use heavy cream or heavy whipping cream; in the UK, whipping cream (double cream also works but whips faster, so watch it).

Mix the butter, powdered sugar, salt & vanilla sugar, then work in the egg yolk. Finally, add the flour and bring everything together into a dough.
Press the shortbread dough flat, cover it and chill for at least 1 hour.
Preheat the oven to 300°F (150°C) convection (fan). Line a large baking sheet (about 16 × 14 inches / 40 × 35 cm; a US half sheet pan, 18 × 13 inches, works too) with parchment paper.
Before rolling, briefly knead the dough once more with a little patience, then roll it out on a floured work surface and cut out the cookies.
Place the cut-out cookies on the baking sheet and pre-bake them in the preheated oven for about 8 minutes. In the meantime, make the meringue.

Beat the egg whites, adding the powdered sugar a little at a time. Keep beating until you have a firm, creamy meringue, then transfer it to a piping bag and pipe it onto the cookies.
Then keep baking the cookies until the meringue is firm.

Bring the cream to a boil and pour it over the couverture chocolate. Let it stand for 2 minutes, then stir into a creamy ganache and leave it until it has cooled.
As soon as the cookies have cooled, carefully add the filling.

From German Pastry Chef. Full recipe with photos: germanpastrychef.com/recipes/burgenland-cookies/