Preheat the oven to 375 degrees F.
In a large bowl, whisk together 4 cups flour, 1/2 cup sugar, 1 and 1/2 teaspoons baking soda, and 1 and 1/2 teaspoons kosher salt.
Use a pastry cutter to blend in 1/4 cup cold butter until you have pea-sized pieces of butter throughout.
In a glass measuring cup, add 1 and 1/2 cups buttermilk. Add in 1 egg and 1 egg yolk. Whisk together.
Add the buttermilk mixture to the flour and combine with a rubber spatula.
Turn the mixture onto a floured surface and knead just once or twice to bring it together. Shape into a 6 or 7 inch circle. Shaggy dough is good, don't knead too much.
Transfer the loaf to a greased baking sheet or cast iron skillet. Use a serrated knife to slice an X into the top, about half inch deep. This allows heat to penetrate to the center of the bread.
Bake at 375 for 40-50 minutes, until a thermometer reads 180 degrees F.
Brush the top with more melted butter. Let cool slightly before slicing. Top with butter and jam, or butter and brown sugar, or leave plain and eat with Corned Beef and Cabbage!