Dissolve the vegetable shortening in the milk in a bowl and cool to lukewarm. Stir in the eggs, 1 cup sugar, potatoes, and salt. Dissolve the yeast in lukewarm water and stir onto the potato mixture. Stir in the flour, raisins, and nuts. Mix thoroughly for 5 minutes by hand. Cover with plastic wrap and let rise in a warm, draft-free place for 1 hour.
Turn out onto lightly floured surface. Roll into a 1/2-inch thick rectangle and spread with the butter. Sprinkle with the 1 remaining tablespoon sugar and the cinnamon. Roll like a jelly roll and slice 12 equal slices. Place slices flat in 12 by 8-inch baking dish. Cover with a tea towel and let rise until double in bulk, about 30 minutes.
Preheat the oven to 350 degrees F. Bake for 30 to 35 minutes, until golden brown. Transfer to a wire rack to cool.
The Secrets of Jesuit Breadmaking, HaperPerennial, 1995