Preheat the oven to 400 degrees.
Line a baking sheet with parchment paper.
Everything can be mixed together in one large bowl.
In the large bowl, whisk together 4 cups of flour and 1 tsp of baking soda.
Add the softened butter (very soft!), brown sugar, egg, and buttermilk to the flour and baking soda. Mix together using a wooden spoon or a spatula. Make sure to mix up from the bottom.
If the mixture gets too thick to mix with the spoon, you can finish mixing with your hands.
Once the dough is combined, add the raisins. I also mixed these in my hand.
Lightly flour your work surface and turn out the dough.
Knead just a few times and then form circle with the dough. You don't need to flatten it out.
Place the dough on the prepared baking sheet.
Score an X in the top with a very sharp knife.
Beat together the second egg and 1 tablespoon of water in a cup.
Spread the egg wash over the surface of the bread dough with a pastry brush.
Bake the bread until the center is no longer gooey with a wooden skewer is poked through the middle, about 55 minutes. Make sure you try this is a few spots. In addition, Irish soda bread is cooked at an internal temp of about 200-205 degrees F. I used a cooking thermometer to test it out. NOTE: All ovens are different. I would probably start checking for doneness at 45 minutes.