In a mixing bowl, mix together flour, salt, sugar, baking soda, and baking powder. If you’d desired, stir in Parmesan and rosemary. Whisk egg on the side of the bowl and combine with softened butter. It will be crumbly at first. Then quickly stir in buttermilk, mixing just enough to form a homogeneous dough.
Transfer to a lightly floured surface and quickly knead for 5 to 8 times maximum. Shape into a flat round or oval shape! Score an X on the top center (about ¼-inch deep if baking or 1/3-inch deep if cooking bread in the slow cooker). Transfer right away to either a baking sheet or cast iron skillet lined with parchment paper, or to a lined slow cooker.
IF COOKING IN THE CROCKPOT: Brush bread with buttermilk and cook on high for 2 ½ hours, or until a toothpick inserted in the center comes out clean. For a browned crust, brush crockpot bread with olive oil or melted butter and then broil bread on the middle rack of the oven on top of a lined baking sheet for 3-5 minutes or until lightly brown.
IF BAKING: Bake in a preheated oven at 375 degrees F (190 degrees C) for about 45 minutes, or until a toothpick inserted in the center comes out clean and the top has browned. For a moist and softer crust, brush bread with extra buttermilk before baking and also every 20 minutes while baking.