In a large bowl of electric mixer, dissolve the yeast and 1 teaspoon sugar in the warm water. Let stand until foamy, 5 to 10 minutes.
Add the remaining 1/3 cup sugar, eggs, butter, sour cream, vanilla, salt and 1 ½ cups flour to the bowl with the yeast. Beat at medium speed with a dough paddle for 5-7 minutes, adding an additional ½ cup of flour at a time as necessary, until you have a soft but pliable dough (you’ll know when the dough looks just a little less firm than raw pizza dough).
Turn out the dough onto a lightly floured surface. Clean and grease bowl with additional butter. Knead the dough for 4 to 6 minutes, or until the dough feels soft and buttery, but not sticky. Place the dough in the greased bowl, turning to coat all sides. Cover with a slightly damp towel and let rise in a warm draft-free place until doubled in bulk, about 1 ½ hours.
Butter a 13-inch length of parchment paper; set aside. Generously grease a 9” x 13” baking pan.
Prepare the Maple Topping: combine the maple syrup, brown sugar, butter, and salt in a small bowl, and pour into the prepared pan. Sprinkle the bottom of the pan evenly with the chopped pecans; set aside.
Prepare the Cinnamon-Nut Filling: Toast the chopped pecans in a small skillet set over medium heat for 3 minutes, stirring occasionally, until they are just fragrant. Transfer the toasted nuts to a small bowl to cool slightly, then add the brown sugar and cinnamon. Stir to combine, and set aside.
On a lightly floured surface, punch down and roll out the dough to a large pan-sized rectangle. Spread the top of the rectangle with butter, leaving a ½-inch margin on one of the long sides of the rectangle. Sprinkle the dough evenly with the cinnamon-nut filling. Beginning on the buttered long side, tightly roll the dough up and away from you, jelly-roll fashion. Pinch the seam to seal.
Cut the roll widthwise into 12-15 equal slices. Arrange the buns cut-side down in the prepared baking pan on top of the topping. Cover the top of the buns with the buttered parchment paper. Let the buns rise in a warm draft-free place until doubled in bulk, about 1 hour.
Preheat the oven to 375°F (190°C). Remove the paper on top and bake the buns for 30 minutes, or until golden brown. Let the buns stand in the pan for 1 minute; invert the baked rolls onto a platter or a wire rack set over parchment paper.
Spoon any topping remaining in the pan over the rolls. Let stand 5 minutes, and serve warm.