Preheat oven to 450F. Line a dutch oven* with parchment paper.
In a large bowl, whisk together flour, salt, and baking soda. Add cold butter and cut butter into the flour using a pastry cutter or fork.
Add buttermilk slowly, mixing with a spatula or wooden spoon until it forms a soft dough, similar to a thick batter. Transfer dough onto the parchment paper and form it into a round shape. Score an X into the top of the dough using a bread lame or a sharp knife.
Cover and bake for 35 minutes. Remove the lid and bake for 10-12 more minutes, or until golden brown.
Serve with butter. This bread is best eaten fresh, or on the day it has been made.
Notes
*This can be baked on a baking tray or in a skillet. It will not rise as much as in a dutch oven.
Be sure to use baking soda that is fresh for best results.
Do not overmix the dough.
Keep Irish soda bread at room temperature for up to 2 days (but it’s best eaten warm and fresh!).
Freeze the loaf, or slices, wrapped in plastic wrap and then placed into zippered bags for up to 2 months.