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 mashed sweet potato, 1/3 cup of sugar, greek yogurt, 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 caramel sauce. In a medium saucepan, melt the butter over medium heat. Add the brown sugar and stir until incorporated.

Turn off the heat. Add the maple syrup, heavy cream, water, and salt. Whisk it all together until smooth. Pour the caramel sauce into a 9x13-inch baking dish, tilting the dish so that the sauce coats the sides. (The sauce is basically greasing the pan, so make sure you coat it well.) Sprinkle the chopped pecans evenly over the sauce; set aside.

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.

With a butterknife (or your fingers), spread butter evenly over the entire surface of the dough. Sprinkle the brown sugar over it, followed by the cinnamon and chopped pecans. Lightly pat it down with your fingertips to help sugar and pecans adhere to dough. Roll dough tightly into a log (from long side to long side), 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 caramel sauce. Cover tightly with plastic wrap--make sure to coat plastic wrap with cooking spray so that it doesn't stick to the rolls as they rise.

Allow the rolls to rise again in a warm place until doubled in size, about 1 hour.

Place covered rolls in the refrigerator for up to 16 hours. Before baking, let the rolls sit at room temperature until they have nearly doubled in size, about 1-2 hours.

For either version, bake at 375ºF for 15 minutes, or until golden. Tent sticky buns with aluminum foil, and continue to bake for an additional 10-15 minutes, or until baked through.

Allow the sticky buns to cool in the baking dish for 20 minutes. Place a serving dish on top of the pan, and carefully invert pan. Be careful as the caramel sauce will be hot. Remove baking dish, and scoop any run-off sauce back over the buns with a spoon or spatula. Serve immediately.

The sticky buns are best eaten the day of baking but can be stored, covered, at room temperature for up to 2 days.