Preheat oven to 400 degrees. Place rack in the center of the oven. Grease a baking sheet or line with parchment paper.
In a large bowl, sift together flour, baking soda, baking powder, salt, and sugar.
Add buttermilk, melted butter, and raisins or caraway seeds, if desired. Stir until incorporated.
Knead the dough with your hands just until it forms a cohesive ball. Divide dough into 2 evenly-sized loaves and place on the prepared baking sheet.
Using a sharp knife, cut a large X on the top of each loaf.
Bake for 30-35 minutes, until cooked through. You may need to cover the bread with foil during the last 5 minutes of baking to avoid overbrowning. When cooked through, the internal temperature of your bread should be about 190 degrees.
Notes
In the A Bountiful Kitchen Cookbook, we list two buttermilk substitutions: Mix ½ cup plain, unsweetened Greek yogurt (whole is best) and ½ cup milk (we prefer whole) orPour 1 tablespoon lemon juice or white vinegar into a measuring cup and add enough milk to measure 1 cup. Stir, then let sit for 5 minutes. (it's essential to let the mixture sit at least 5 minutes before using.)