Pinca or Sirnica
In a small bowl or measuring cup, combine yeast, 1 tablespoon sugar and warm milk.
Stir with a fork, cover and set aside to become foamy. Meanwhile, in a separate small bowl, combine raisins with grape brandy and set aside.
In a large bowl, cut the cold butter into the flour until fine crumbles result. Add the sugar, egg yolks, yeast mixture, zests and vanilla.
Knead on medium speed until dough forms into a ball.
Add the raisins and the soaking liquid, and continue to knead on low speed until raisins are distributed evenly and dough is smooth.
Add more warm milk if too dry or more flour if too wet.
Scrape down the sides and cover bowl with greased plastic wrap and let rise in a warm place until doubled in size. This can take up to 2 hours.
When dough has doubled, punch it down and turn it out onto a lightly floured work surface. Divide the dough in half and shape each into a round loaf.
Place each round loaf onto a parchment-lined baking sheet pan, spacing well apart. Cover with greased plastic wrap and let rise until doubled in size. This can take up to 2 hours.
Heat the oven to 180°C Brush the tops of the loaves with the eggwash. Then, using scissors, cut a deep "X in the tops to form a cross shape.
Sprinkle with coarse sugar, if desired. Bake 30 to 45 minutes, but start checking for doneness after 25 minutes.
An instant-read thermometer should register at least 190 degrees when plunged into the middle of the bread.
Remove from oven and from sheet pan, and cool completely on a wire rack.