Cut a large sheet of parchment paper and press it into the bottom of a 6-quart slow cooker, leaving enough overhang to act as handles. Lightly brush the parchment with some of the finishing butter.

In a large mixing bowl, whisk together the self-rising flour, sugar, baking soda, and salt.

Pour in the buttermilk and melted butter. Stir gently with a wooden spoon or sturdy spatula just until the flour is incorporated and a soft, slightly sticky dough forms. Do not overmix.

Lightly flour your hands and gently gather the dough into a thick round or slightly oval loaf, approximately 6–7 inches across. Do not knead.

Place the loaf in the center of the parchment-lined slow cooker. Lightly brush the top with melted butter.

Lay a clean kitchen towel across the top of the slow cooker and place the lid securely over it, making sure the towel is pulled up and kept completely away from the exterior and heating elements. The towel absorbs condensation and helps prevent moisture from dripping onto the bread.

Cook on HIGH for approximately 1 hour 45 minutes–2 hours 15 minutes. Begin checking at 1 hour 45 minutes. The loaf is done when the center registers 195–200°F on an instant-read thermometer and a tester inserted into the center comes out without wet dough.

Preheat the broiler. Using the parchment as handles, carefully lift the bread from the slow cooker and transfer it to a baking sheet. Remove the parchment and lightly brush the top with additional melted butter.

Broil for approximately 2–3 minutes, watching continuously, until the top is attractively golden brown.

Brush the hot loaf with a final light coating of melted butter. Let cool for at least 15 minutes before slicing. Serve warm or at room temperature.