In a small saucepan, cook potatoes, covered, in enough boiling water to cover for 15 to 20 minutes or until tender; drain, reserving 1/2 cup of the cooking liquid. Using a fork, mash the potatoes; set aside. Add buttermilk, the 1/4 cup butter, the sugar, and salt to the hot cooking liquid; heat until warm (120 degree F to 130 degree F) and butter almost melts.

In a large bowl, stir together 1-1/2 cups of the flour and the yeast. Stir in the buttermilk mixture and mashed potatoes. Beat with an electric mixer on low speed for 30 seconds, scraping bowl. Beat on high speed for 3 minutes. Stir in as much of the remaining flour as you can.

Turn dough out onto a lightly floured surface. Knead in enough remaining flour to make a moderately stiff dough that is smooth and elastic (6 to 8 minutes total). Shape dough into a ball. Place in a buttered bowl; turn once. Cover; let rise in a warm place until double (about 1 hour).

Punch dough down. Turn dough out onto a lightly floured surface. Divide dough in half. Cover; let rest for 10 minutes. Meanwhile, lightly grease three baking sheets (or line baking sheets with parchment paper).

On a lightly floured surface, roll each portion of dough into a 10x6-inch rectangle (3/4-inch thick). Cut each rectangle of dough into fifteen 2-inch squares. Place squares 2 to 3 inches apart on the prepared baking sheets. Brush tops with the 2 tablespoons melted butter. Cover with plastic wrap; let rise in a warm place for 15 minutes.

Bake in a 375 degree F oven 15 to 18 minutes or until golden. Immediately remove rolls from baking sheet. Cool slightly on a rack. Serve warm. Makes 30 rolls.

Prepare as above. Cut each rectangle of dough into fifteen 6x3/4-inch strips. Gently pull strips into a 8-inch-long ropes. In a small bowl, combine 3/4 cup olive oil, 3 tablespoons snipped fresh rosemary, and 2 cloves garlic, minced. Dip each rope into oil mixture. Tie into a loose knot. Place knots 2 to 3 inches apart on the prepared baking sheets. Sprinkle with coarse or kosher salt. Cover with plastic wrap; let rise in a warm place for 15 minutes. Bake in a 375 degree F oven about 15 minutes or until golden. Immediately remove rolls from baking sheet. Cool slightly on a rack. Serve warm. Makes 30 knots.