Combine the yeast, white sugar, and water in a large mixing bowl. While this is proofing, stir 1 stick of the butter and the salt into the warm milk. (The butter does not need to melt completely.) Add to the yeast mixture. Stir in the whole eggs and egg yolks. Beat with a wooden spoon or with the hands to blend thoroughly. Add the flour, 1 cup at a time, stirring well after each addition. (After the first 5 cups it will get harder to incorporate the flour and the dough will be very sticky.) Turn out on a floured board, and using a baker’s scraper or large spatula, scrape under the flour on the board, lift the dough, and fold it over. Continue this procedure, adding more flour until the dough is no longer sticky and can be kneaded with your hands. Knead a full 10 minutes, until the dough is elastic and pliable. Shape into a ball and put in a buttered bowl, turning to coat all over with butter. Cover with plastic wrap and set in a warm, draft-free place to rise until doubled in bulk. Punch the dough down and let rest for 5 minutes. Turn out on a lightly floured board (using about 1 tablespoon flour) and again shape into a ball. Let rest for another 5 to 10 minutes. Meanwhile, butter a 10-inch tube pan.

In a saucepan, melt the second stick of sweet butter with the brown sugar and currants. Pinch off enough dough to make golf ball-sized balls. Roll the balls in the butter mixture, line the bottom of the tube pan with them, and continue to arrange them in loose layers. Pour what is left of the butter mixture over the top. Cover loosely with a foil tent and let the dough rise to the top of the tube pan. Bake in a preheated 375° oven for about an hour; it may take a minute or two more. Tap the top: it will sound hollow when the bread is ready. (If the top browns a little too much, don’t worry, because this will be served inverted.) Unmold and let cool thoroughly before slicing, or serve warm and pull apart.