How to Make It
In a medium bowl, combine the yeast with the warm water and 1 teaspoon of the sugar and let stand until foamy, about 5 minutes. Whisk in the 6 eggs. In the bowl of a standing mixer fitted with the dough hook, mix the 4 1/2 cups of sifted flour with the salt and the remaining 1/4 cup of sugar. Add the egg mixture and beat at medium speed until the dough is just moistened and very stiff. Add the butter a few cubes at a time, waiting until it is partially kneaded into the dough before adding more. Continue kneading until the butter is fully incorporated and the dough is silky, 8 to 10 minutes. Transfer the dough to an oiled bowl, cover with plastic wrap and refrigerate until chilled and slightly risen, at least 2 hours or overnight.
Preheat the oven to 350°. Spread the pecans in a pie plate and toast for about 8 minutes, until fragrant and browned. Let cool, then finely chop the pecans. Transfer to a medium bowl and stir in the brown sugar and cinnamon.
Line 2 baking sheets with parchment paper. On a floured surface, cut the dough into 2 pieces. Working with 1 piece at a time (while keeping the other refrigerated), roll the dough out to a 12-by-16-inch rectangle. Transfer the dough to a baking sheet and refrigerate until chilled. Repeat with the remaining dough.
Spread half of the sour cream over one sheet of dough, leaving a 1/2-inch border all around. Sprinkle with half of the pecan filling. Brush the long sides with some of the egg wash. Roll up the dough from a long side into a tight cylinder and pinch the ends to seal. Freeze the dough log until it is chilled, about 2 hours. Repeat with the remaining dough and filling. Cover and refrigerate the remaining egg wash.
Transfer the logs to a work surface and cut each one into 12 even slices. Set the slices on the baking sheet, cut sides up. Cover with plastic wrap and freeze until firm, at least 3 hours and preferably overnight.
Unwrap the rolls and let stand at room temperature for 1 hour.
Preheat the oven to 350°. Brush the tops and sides of the rolls with the egg wash and bake in the center of the oven for 35 to 40 minutes, until golden and risen.
In a medium bowl, using an electric mixer, beat the confectioners' sugar with the butter, heavy cream and vanilla extract until thick and smooth. Spread the sugar glaze on the hot cinnamon rolls and let cool for 20 minutes before serving.