Mix potatoes and milk until smooth. Add 1/2 cup butter, 1 cup sugar and salt. Heat to lukewarm (about 11 O deg). In a large bowl combine yeast, water and remaining 2 tsps sugar. Let stand until foaming (about 10 minutes). Add potato mix, 4 cups flour, eggs and vanilla. Beat until smooth. Gradually stir in additional 3 1/2 to 4 cups flour. Turn dough on heavily floured board and knead until smooth and elastic (15 minutes). Add more flour if needed. Let rise 1 1/2 hours. Punch down, kneed to remove bubbles. Divide. Melt remaining butter. Roll each portion of dough to a 5x18 rectangle. Brush with 3 tsps of butter and sprinkle with half of the cinnamon filling. Roll up. Cut in 12 pieces, 1 1/2" wide. Place in a 9x13" pan, brush with butter and let rise 35-40 minutes. Bake at 350 degrees 30 minutes.