Grandma's Irish Soda Bread

 1 and 3/4 cups (420ml) buttermilk1

large Eggland's Best egg

and 1/4 cups (515g) all-purpose flour (plus more for your hands and work surface) (measured correctly)

granulated sugar

baking soda

salt

and 1/2 Tablespoons (65g) unsalted butter, cold and cubed

raisins (I use half golden, half regular)2