Sprinkle the yeast into the warm water in a large mixing bowl. Set aside to proof.
If using the brandy, mix into the currants and set aside to macerate.
Melt the butter, then stir in milk, sugar and salt, stirring to dissolve the sugar. Cool, then stir into the yeast.
Beat the egg. Measure and reserve 1 tablespoon for brushing the buns before baking. Stir remaining egg into the yeast mixture, along with the currants.
Mix the flour with the spices. Add gradually to the yeast mix, adding just enough to make a soft dough. If additional is required, add by the tablespoon until the dough can be kneaded.
Turn out onto a lightly floured surface and knead until smooth and elastic, adding only enough flour to keep from sticking. The mixing and kneading can be done using a strong mixer with dough hook.
Place the dough into a lightly buttered bowl, brush top with butter and cover with a clean kitchen towel. Let rise in a warm place until doubled, about 1 hour.
Turn out and divided evenly into 8 pieces. Shape each piece lightly into a ball. Place the balls of dough onto a baking sheet lined with parchment paper. Cover and set aside to rise, about 45 minutes. Preheat the oven to 350 degrees F. Brush the risen rolls lightly with the reserved beaten egg.
Bake for 15-20 minutes, until puffed and brown. Cover with a sheet of foil if the rolls are browning too quickly.
Remove rolls from the oven and cool on a wire rack.
Beat the confectioner's sugar into the butter with the vanilla. Add milk by drops until spreadable consistency. Additional confectioner's sugar may be added as desired for a stiffer icing for piping. Spread or pipe onto the warm rolls.