Bulgaria's traditional Easter bread - a soft, brioche-like sweet loaf braided and baked golden, studded with rum-soaked raisins and perfumed with lemon zest and vanilla - soaking the raisins in rum first, rather than adding them dry, is what keeps them plump and flavorful instead of drying out and turning tough inside the baked dough.
1.Soak the raisins in the rum for at least 30 minutes, ideally 1-2 hours, so they plump up and stay soft and flavorful once baked into the dough.
2.Dissolve the yeast and 1 tbsp of the sugar in the warm milk and let sit for 5-10 minutes until foamy.
3.In a large bowl, whisk together the flour, remaining sugar, and salt. Add the yeast mixture, 4 eggs, melted butter, lemon zest, and vanilla, and knead for 10-12 minutes until you have a smooth, elastic, slightly tacky dough.
4.Drain the raisins and knead them into the dough until evenly distributed.
5.Cover and let rise in a warm place for 1.5-2 hours, until doubled in size.
6.Punch down the dough, divide into 3 equal strands, and braid them together, tucking the ends underneath. Place in a greased loaf pan or on a baking sheet.
7.Cover and let rise again for 45-60 minutes, until puffy.
8.Preheat the oven to 350°F. Brush the loaf all over with the beaten egg and sprinkle with the 2 tbsp sugar.
9.Bake for 35-40 minutes, until deep golden brown and a skewer inserted into the center comes out clean, tenting with foil partway through if the top browns too quickly.
10.Let cool completely on a wire rack before slicing.