This is the recipe my Great Grandma Wolf made and served me when I would spend the night at her house in Glendora, California. I have taken liberties by adding the mac nuts and the rum. When I was a little girl my Great Grandma Wolf would give me buttered rum Lifesavers to keep me quiet in church, so the flavor is homage to her. These freeze well and can be re-heated. You can also make and proof the dough the night before and then refrigerate the dough. If you do this, it will take about 2 hours for the rolls to rise in their second fermentation.
Add the warm water to the yeast and soak 10 minutes.
Scald milk; pour over the shortening. Add sugar, zest and salt and cool to tepid. Add the dissolved yeast and beaten egg. Add 4 cups flour adding one at a time beating after each addition.
Dough should be soft yet firm enough to handle. Knead on floured board until elastic and smooth. Avoid too much flour. Turn dough into well oiled bowl. Let rise for 1-1/2 hours.
Softly press dough down and shape into a rectangle. Roll dough out into a rectangle about 18 inches wide and 8 inches tall. Cover with the soft butter. Layer with a generous layer of sugar (brown or a combo of vanilla sugar and maple sugar.) Sprinkle on cinnamon and evenly distribute the nuts. Roll up jellyroll fashion.
Using a piece of thread or dental floss cut off slices about 1-1/2 inches thick. Place slices in a full side sheet pan lined with a silpat pad (or you can spray the pan with PAM.) Cover with plastic wrap and let rise until rolls fill the pan generously. This should take about an hour.
Bake in a 350 degree F oven about 20 – 30 minutes. Do not over bake rolls. Make sure the center rolls are cooked all the way through by testing with an instant read thermometer. It should read about 200 degrees. Allow to cool at least 15 minutes before frosting.
For the Frosting: Using a mixer with whisk attachment whip the mascarpone, then add the powdered sugar and rum. Whip till fluffy. Spread over warm rolls as soon as they are placed on a plate to let the frosting melt and run into the rolls.