In a large bowl, stir four and one-half teaspoons of active yeast and one cup of buttermilk. Allow to rest for five minutes.
In the bowl of a stand mixer, whisk two beaten eggs, one and one-half cups of sweet potato puree, six tablespoons of melted butter, three tablespoons of white sugar, and one teaspoon of salt together. Add the yeast mixture and mix until well combined.
Using the dough attachment with your stand mixer, add three cups of Bisquick, one cup at a time, until a thick dough forms.
Slowly add the remaining Bisquick, a bit at a time, until the dough is stiff enough to knead.
Turn dough out onto a lightly Bisquick floured surface. Continue to knead, adding more Bisquick if necessary, until you have a smooth, elastic dough. The dough should not feel tough.
Place the dough into a greased bowl. Turn the dough in the bowl to coat the entire ball of dough with oil.
Cover with plastic wrap and let rise until doubled.
Divide the dough into two equal pieces. Then, divide each of those into twelve equal pieces, depending on how big you would like your rolls.
Roll each piece of dough to form smooth balls. Place the rolls on parchment lined baking sheets and cover with plastic wrap. Allow the rolls to rise for thirty minutes.
Preheat the oven to 400 three hundred and fifty degrees and bake the rolls for thirty minutes, or until golden on top.
Rotate the baking sheets halfway through baking if you cannot bake them all on the same rack.
Brush the rolls with melted butter, and add a sprinkling of flaked sea salt if desired.