Yam Cinnamon Rolls

5 tsp. active dry traditional yeast (about 2 pkgs of .25 oz or 7 g.), NOT rapid-rise yeast!
1/4 C. warm water
1 tsp. granulated sugar
1/2 C. slightly warm buttermilk (you can also make your own buttermilk by adding 2 tsp. lemon juice to 1/2 C. regular milk and letting it "curdle" a few minutes)
2 tsp. vanilla
1 egg
1.5 C. cooled boiled & mashed yam (wash & prick yams all over with fork, cover w/ water and boil (or cover w/ foil and bake) till tender/easily pierced with fork, drain, peel skin, and then mash)--can also use sweet potato
1/2 C. brown sugar (dark or light)
1Tbs. salt
1 tsp. cinnamon
1/4 C. canola or vegetable oil
7 C. unbleached all-purpose flour
1/2 C.  (about 1/2 stick) unsalted butter, melted

Cinnamon Filling:
1/2 C. granulated sugar (if you like a little less sweet, you can cut sugars to 1/4 C. each)
1/2 C. brown sugar
2 Tbs. cinnamon
1/2 C. currants, raisins, dried cranberries or other berries (I used dried cranberries; if dried fruit is very hard, soak in enough hot water to barely cover until moist and then drain before using)

Cream cheese frosting (optional, but yummy!):
6 Tbs. unsalted butter, softened but still cool
3 oz (about 1/3 C.) cream cheese, softened but still cool
3 C. (12 oz) powdered sugar
4 Tbs (2 1/4 oz) regular milk OR coconut milk (for coconut flavor)

1. Combine yeast, warm water and 1 tsp. granulated sugar in bowl; set aside till foamy, about 5 min.
2. Blend together buttermilk, vanilla, egg, mashed yam, brown sugar, salt, cinnamon, and oil in a large bowl (if you have a mixer, this makes this step a lot easier!).  Stif in the yeast mixture, then the flour, 1/2 C. at a time, until a soft dough forms and cleans the side of the bowl as you mix it.  (if using a bowl mixer, change from the paddle attachment to the dough hook when you add the flour)
3. Transfer the dough to a lightly floured flat surface and knead for about 5 minutes, or until springy and smooth.  Add 1 Tb of flour at a time to keep the dough from sticking, if necessary
4.  Put the dough into an oiled mixing bowl, rotate ball of dough so oil coats it, and cover bowl with plastic wrap (I find using a plastic shower cap like the ones you get in hotels works great).  Put the bowl in a warm place, like on top of your stove (don't turn it on), and let dough rise until doubled (about 1.5 to 2 hours--can go to 3 hrs). 
5.  Divide the dough into 2 equal portions.  Pat or roll each portion into a thick rectangle, about 9" x 13".  Spread each rectangle with 1/2 of the melted butter, leaving about 1/2 an inch on one short edge unbuttered.
6. Sprinkle half of your filling mixture (see below) over  the buttered part of the rectangle.  Press currants/dried fruit into the dough.  Roll up each rectangle into a cylinder, toward the unbuttered edge, so that it will stick  and hold the cylinder together.  Then cut each cylinder into approximately 9-11 rolls (about 3 inches wide each).  Place rolls, cut side up, onto parchment-covered or greased cookie/baking sheets; keep rolls about 2 inches apart.
7.  Cover baking sheet/rolls loosely with a clean dish towel and let rise for about 45 minutes, until doubled.
8.  Preheat oven to 350 degrees Fahrenheit while rolls are rising.
9.  Bake rolls for 22-25 minutes, until light golden brown.
10.  Remove and let cool till slightly warm before frosting. Sprinkle with a few chopped nuts on top, if desired.

To make filling (do this while the dough is rising):
In a medium bowl, combine granulated sugar, brown sugar, cinnamon, and dried fruit. 

To make cream cheese frosting (you can do this while rolls are baking):
Cream together  (use mixer with paddle atachment or handheld mixer) butter & cream cheese on medium speed for 2-3 minutes until ight and fluffy.  Sift 1.5 C. of powdered sugar into the bowl and stir until smooth.  Add remaining powdered sugar and the milk, and stir together till smooth.  This will keep up to 2 weeks, tightly covered, in refrigerator.