In a large bowl, combine 1 1/3 cups flour, 1/2 cup sugar, undissolved yeast and salt. Combine and heat water, milk, butter and the mashed potatoes until very warm - 120 to 130° F. Gradually add to flour mixture. Beat 2 minutes at medium speed of electric mixer, scraping bowl often. Add eggs and 1 cup flour; beat 2 minutes at high speed. Stir in enough remaining flour to make a soft dough. Knead on a lightly floured surface until smooth and elastic, about 10 minutes. Cover; let rest 10 minutes.
Roll dough to an 18 x 12-inch rectangle. Brush with the melted butter. Sprinkle with the filling made by mixing the 1/4 cup sugar, cocoa powder and cinnamon spice fans might want more cinnamon; if so, dribble on more melted butter, then sprinkle with additional sugar and cinnamon.
Beginning at long end of dough rectangle, roll up tightly. Pinch seam to seal. Cut into 12 pieces. Place, cut sides up, into 12 greased muffin cups. Cover; let rise in a warm place until doubled, about 1 hour.
Bake at 375° F for 15 to 20 minutes or until done. Remove from cups and cool on wire racks. Sift confectioners' sugar over the tops.Servings: