In a glass measuring cup, combine the yeast, water*, and 1 teaspoon of sugar; set aside to foam for about 5 minutes. In the bowl of an electric mixer fitted with the paddle attachment, combine the pumpkin purée, 1/3 cup of sugar, sour cream, milk, melted butter, egg, pumpkin pie spice, and salt.
Switch to the dough hook, and add the yeast mixture and 3 cups of the flour. Mix the dough on low and allow it to knead for about 6-7 minutes. If dough is still too soft, add more flour, 1 Tablespoon at a time, until dough just cleans the bowl, but is very soft. It should still stick to the bottom of the bowl.
Coat a large bowl with cooking spray and place dough in bowl. Seal tightly with plastic wrap. Place bowl in a warm place and allow dough to rise until doubled in size, about 2 hours.
In the meantime, make the toffee sauce. In a medium saucepan, melt the butter over medium heat. Add the brown sugar and honey, stirring until incorporated.
Whisk in the heavy cream, and continue to cook without stirring until mixture reaches 228ºF. Remove from the heat, then stir in vanilla, pumpkin pie spice and salt. Allow to cool slightly.
Chop 1/2 cup of the toasted pecans, then stir into the toffee sauce along with the rest of the whole toasted pecans. Pour mixture into a greased 9x13-inch baking dish, spreading it evenly; set aside.
Make the cinnamon brown sugar filling by combining the butter, brown sugar, pumpkin pie spice and cinnamon together in a bowl.
After dough has doubled in size, punch it down. Turn dough out onto a floured Silpat or floured countertop. With a rolling pin, roll it out to an 18x15-inch rectangle.
Spread the filling evenly over the entire surface of the dough. Roll dough tightly into a log, ending with the seam side down. Pinch the ends to seal.
Using plain, unwaxed dental floss (or a bench scraper), slice the rolls into 12 evenly-sized rolls. Arrange the rolls cut-side down in the baking dish on top of the toffee-pecan sauce. Cover tightly with plastic wrap.