In a large bowl, beat together the butter and sugar until smooth. Add the eggs, and beat on high speed until the mixture is thick and light-colored, about 2 minutes. Stir in the baking powder, baking soda, and salt, then 1 cup of the flour. Gently beat in half the buttermilk (or milk/yogurt mixture), then another cup of the flour. Add the remainder of the buttermilk, and the final cup of flour, mixing until smooth. Stir in the currants and caraway seeds.
Spoon the mixture into a lightly greased 8" x 3 1/2" round pan (or a 9" x 3" round pan), one whose capacity is at least 5 1/2 cups. A souffle pan or panettone pan is a good choice. Drizzle the milk atop the batter, and sprinkle with the sugar.
Bake the bread in a preheated 325°F oven for 1 hour 15 minutes, or until a cake tester inserted into the center comes out clean. Tent a sheet of aluminum foil over the top for the final 15 minutes, if it appears to be browning too quickly. Remove the bread from the oven, wait about 5 minutes, then carefully turn it out onto a rack to cool. Allow the bread to cool for at least 1 hour before slicing. Yield: about 12 servings.
Alternatively, spoon the batter into a 9 x 5-inch loaf pan. Bake the bread in a preheated 375°F oven for 45 minutes to 1 hour, or until a cake tester inserted into the center of the loaf comes out clean.