Preheat oven to 375°F. Grease 9" pie pan and set aside.
Add buttermilk, butter, sugar, and orange zest to jar and secure lid. Press "Pulse" 6–10 times or until butter is size of coarse crumbs. Add baking powder, baking soda, salt, and ½ of flour to jar. Secure lid and pulse 2–3 times. Add remaining flour and currants to jar and secure lid. Pulse 4–6 times or until flour and currants are incorporated.
Transfer dough by tilting jar over pie pan and using spatula; shape dough (dough won't come to edges of pie pan). Use serrated knife to lightly cut an X into top of loaf. Bake for 40–50 minutes or until toothpick inserted in center comes out clean. Serve warm or at room temperature.