Dough:
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)