Preheat oven to 375°. Line a baking sheet with parchment paper and set aside.
In the bowl of your stand mixer using your paddle attachment, stir the flour, sugar, salt, baking powder and baking soda on low speed for a few seconds to combine. Add in the cold butter cubes and mix on medium speed for 3 minutes until butter is coarse and crumbly. Turn speed to low and add raisins and caraway seeds just for a second to evenly disperse them throughout the flour mixture.
In a separate bowl, whisk the buttermilk and egg together until fully combined. Switch over to the dough hook and gradually add buttermilk and add to flour mixture on low speed. Knead for 1 minute or until the dough is together. If the dough is still sticky and unworkable, add up to 1/4 cup more as needed. Please keep in mind though, that the dough should be slightly sticky, but it shouldn't stick to your hands. After a minute, shape dough into a ball and knead on a lightly floured counter for another minute until you have a soft, smooth dough. Shape the dough into a ball and smooth some flour over the top so it has a very light coating.
Cut a 1/4 inch deep "X" into the top of the dough.
Bake for 45 minutes - 1 hour or until top is golden brown. The bread is done when you tap on the outside and it sounds hollow. If you are still unsure, stick a skewer or similar object through the side to the middle and make sure it's cooked through.
Transfer bread to a wire rack to cool a bit then cut and serve. Best served warm with butter.
Traditional Irish Soda Bread will stay fresh for up to 3 days stored in an airtight container at room temperature.
*Be sure to use REAL buttermilk, no substitutions.