For dough, stir together 4 cups flour and yeast in a large bowl; set aside. Combine buttermilk, sugar, ¼ cup butter, shortening, and salt In a small saucepan. Cook and stir over medium heat just until butter and shortening are melted. Remove from heat; stir in cold water. Add buttermilk mixture to flour mixture along with the eggs. Using a wooden spoon, stir until a soft dough forms.

Turn dough out onto a lightly floured surface. Knead in up to 3 tablespoons more flour for 5 minutes to make a soft, but not sticky, dough. Place dough in a lightly greased bowl; turn to grease surface of the dough. Cover; let rise in a warm place about 1 hour or until double in size.

Lightly spray sides of a 3-quart rectangular baking dish with nonstick spray. For topping, in a medium saucepan combine 2 cups brown sugar, cream, 1 tablespoon butter and vanilla. Bring mixture to boiling; reduce heat. Gently boil for 3 to 4 minutes. Pour topping into prepared dish. Scatter pecans on top.

Turn dough out onto a lightly floured surface. Gently roll out on a lightly floured surface to an 18-by-15-inch rectangle. Spread the softened ¼ cup butter evenly over dough. In a small bowl, combine ½ cup brown sugar and cinnamon; sprinkle evenly on dough. Tightly roll the dough beginning at one long side, keeping the roll as uniform as possible. Pinch the edges to seal. Using a serrated knife, trim both ends. Then cut roll into 12 even slices. Arrange rolls in baking dish, evenly spacing them 4 rows of 3 each. Use your hands to gently press the rolls into the pecans. Cover dish loosely with buttered plastic wrap and let rolls rise until nearly double (about 40 minutes).

Preheat oven to 350°. Uncover rolls and bake for 30 to 35 minutes or until light brown. Let stand in dish on wire rack for 5 minutes. Invert onto serving platter. Serve warm.

Make-ahead directions: Prepare and bake rolls as directed. Cool rolls completely. Wrap in foil and store at room temperature overnight. Unwrap rolls. Place rolls on a foil-lined baking sheet. Bake in a 350° oven for 15 to 20 minutes or until warm.