This is the perfect Irish soda bread recipe because you can adjust it to suit your needs. Sweeter? Add some sugar. Want currants and caraway? Have at it!
Coat a cast iron skillet with oil.
Cut cold butter into cubes and freeze for 5 minutes.
Mix in a bowl all-purpose flour, whole wheat flour, baking powder, baking soda, salt, and sugar with a whisk.
Add butter and use fingers to pinch to incorporate.
Add buttermilk and dried blueberries. Stir to combine.
Use hands to gather dough into a rough, shaggy ball and place in skillet.
Score the top with an X and brush with buttermilk.
Bake for 45-55 minutes at 400°F. Halfway through, if the bread is getting too brown, cover it with foil. Cool for 10 minutes before slicing.