01 - Preheat oven to 400°F. Line a 12-cup muffin tin with paper liners or lightly grease with butter or cooking spray.
02 - In a large mixing bowl, whisk together all-purpose flour, whole wheat flour, granulated sugar, baking powder, baking soda, and fine sea salt until well blended.
03 - In a separate bowl, whisk together buttermilk, egg, and melted butter until fully combined and smooth.
04 - Pour the wet ingredients into the dry ingredients. Add dried currants and orange zest if using. Gently fold together with a spatula until just combined. Do not overmix—some small lumps are acceptable.
05 - Divide batter evenly among the prepared muffin cups, filling each about 3/4 full.
06 - Bake for 18 to 20 minutes until golden brown and a toothpick inserted into the center comes out clean.
07 - Allow muffins to cool in the tin for 5 minutes before transferring to a wire rack. Cool completely or serve warm. Enjoy with Irish butter and jam.