1Preheat the oven to 425?F.
2In a large bowl, stir together the flour, sugar, baking soda and salt. Add the butter and blend it in with a pastry cutter, fork or your fingertips until it’s kind of rubbly, as if you were making pastry. Add the currants or raisins and toss to combine.
3In a small bowl (or glass measuring cup), stir together the eggnog (or buttermilk) and egg with a fork. Add to the flour mixture and stir until you have a sticky dough; turn out onto a floured countertop and knead once or twice, then shape into a rough ball and place on a parchment-lined sheet or in a cast-iron skillet. Cut an X on the top with a sharp knife.
4Bake for 45 minutes to an hour, until deep golden, springy to the touch, and the bottom of the loaf sounds hollow when tapped. (If it’s getting too dark, cover the loaf with a piece of foil while it’s in the oven.) Cool on a wire rack, then cut into wedges to serve while it’s still warm.