1. Cut butter with a sharp knife or pastry blender into 1/4-inch-thick slices. Sprinkle butter slices over flour in a large bowl. Toss butter with flour. Cut butter into flour with a pastry blender until crumbly and mixture resembles small peas. Cover and chill 10 minutes. Add buttermilk, stirring just until dry ingredients are moistened.
2. Turn dough out onto a lightly floured surface; knead 3 or 4 times, gradually adding additional flour as needed. With floured hands, press or pat dough into a 3/4-inch-thick rectangle (about 9 x 5 inches). Sprinkle top of dough with additional flour. Fold dough over onto itself in 3 sections, starting with 1 short end. (Fold dough rectangle as if folding a letter-size piece of paper.) Repeat entire process 2 more times, beginning with pressing into a 3/4-inch-thick dough rectangle (about 9 x 5 inches).
3. Press or pat dough to 1/2-inch thickness on a lightly floured surface; cut with a 2-inch round cutter, and place, side by side, on a parchment paper-lined or lightly greased jelly-roll pan. (Dough rounds should touch.)
4. Bake at 450° for 13 to 15 minutes or until lightly browned. Remove from oven; brush with 2 Tbsp. melted butter.