Remove the yams and syrup from the can. Mash the yams in a small bowl using a fork and set aside. (This will be about 1 cup.) Place 1/2 cup of the yam syrup into a large mixing bowl. Add the milk, brown sugar and yeast. Stir and let set a couple of minutes. To this mixture add 2 tablespoons of butter, pumpkin pie spice, vanilla, salt, and the 1 cup of mashed sweet potatoes. Stir all ingredients together using a baker’s bread whisk or heavy spoon. Add 1 cup of flour and mix inches Add the second cup of flour and mix. The flour should now be added in 1/4 cup increments until the dough pulls together as a ball. Flour a work surface and remove the dough ball from the bowl.
Gently knead the dough with a fold down toward you, push back with the heels of your hand type motion, carefully folding and flipping the dough for about 6 to 8 minutes or until it is satiny and a depressed finger spot springs back. Clean out the mixing bowl and grease it with the remaining melted butter. Rub some of the melted butter on the top of the dough; cover the bowl with plastic wrap. Allow to sit in a warm place for 1 1/2 hours or until double in bulk.
Remove the dough from the bowl and place again on a lightly floured surface. Allow to rest while you make the glaze and filling.
To make the glaze and prepare the pan: with a pastry brush grease the inside of a 9x10-inch round or square baking pan using 1 tablespoon of the melted butter. Combine the rest of the ingredients in a small bowl and cover the bottom of the prepared pan and spread out across a bit up the sides.
To make the filling, combine the pecans, brown sugar, and spice in a small bowl. Roll the dough out to a 12x12-inch rectangle. Brush the dough with the melted butter. Spread the praline filling evenly across the dough. Roll up jellyroll style so that you end with a 12-inch roll. Slice the roll into 12 even pieces. (The easiest way is to cut the dough in half, and those in half again – and then in thirds.) Place the cut rolls into the prepared pan, so that the swirl of filling is visible on top. (They can also be refrigerated at this point until ready to bake.) Allow the rolls to rise and become “puffy” before baking. This step is important to achieve a light texture on the finished rolls.
Place in oven, turn oven to 350ºF and bake 30 to 35 minutes. Remove from oven, allow to cool for 2 minutes, cover with a large platter, and flip pan over so the sticky buns are now sticky side-up. Enjoy! Chef’s Note: Use caution when flipping the cooked sticky buns over because the filling and syrup are extremely hot. If the buns don’t come out of the pan easily simply place in a warm oven to remelt the glaze and the buns should fall right out.