Mix flour, yeast, and salt in a medium bowl. Add the buttermilk and 1 tablespoon of butter and stir with a wooden spoon until the dough forms a ball.
The dough should rise for about an hour in an oiled bowl covered with a clean dishtowel on a warm countertop.
After doubling, preheat oven to 350°F (177°C) and roll dough into a 16-by-10-inch rectangle on a lightly floured board using a rolling pin.
Mash the minced garlic and parsley with a fork in a small basin with the remaining butter. Apply the garlic butter mixture evenly to the dough, leaving ½ to inch around the edges.
Roll the dough into a log from one long side. Split the log in half to make two long pieces.
Wind the two sections together with the cut sides up and shape the ends into a tight S (see images). Place dough in loaf pan.
Bake till the top is deep golden brown, 35 minutes. Let cool on a wire rack for 20 minutes before serving.