Put 1/4 c. warm water in a large bowl, sprinkle in yeast and stir to dissolve. Mix in 6 T. melted butter, 1/2 c. sugar, salt, egg and potato. Stir well. Add half the flour and mix with a spoon until smooth. Add remaining flour and mix well. Let rise until doubled. Punch down and flatten onto a greased 9 inch square pan. Cover and let rise in a warm place until doubled.
Preheat oven to 400F. Combine brown sugar, 2 T. melted butter, cinnamon, and 1 1/2 tsp. water. With thumb, make depressions in dough about 1 inch apart and fill with brown sugar mixture. Bake 20-25 minutes. Cool, then dust with powdered sugar.
Mom puts a thin half pat of butter on top of each of the brown sugar holes before cooking.