For topping, stir together powdered sugar and whipping cream in a small bowl. Pour into an ungreased 12-inch deep-dish pizza pan or a 13x9x2-inch baking pan. Sprinkle pecans evenly over mixture; set aside.

Roll each thawed loaf into a 12x8-inch rectangle on a lightly floured surface. Brush with melted butter. Stir together brown sugar and cinnamon in a small bowl; sprinkle over both rectangles. Top each with raisins, if desired. Roll up rectangles, jelly-roll style, starting from a long side. Pinch to seal. Cut each log crosswise into 6 slices. Place slices, cut side down, atop pecan mixture in pan. Cover with a towel. Let dough rise in a warm place until nearly double (about 30 minutes).

Bake in a 375 degree F oven, uncovered, until golden, allowing 25 to 30 minutes for unchilled rolls and 30 to 35 minutes for chilled rolls. If necessary, cover rolls with foil the last 10 minutes of baking to prevent overbrowning. Cool in pan on a wire rack for 5 minutes. Loosen edges; invert onto a serving platter. Serve warm. Makes 12 rolls.

Cover with oily waxed paper, then plastic wrap. Refrigerate 2 to 24 hours. Before baking, let the shaped rolls stand, covered, for 20 minutes at room temperature. Remove towel or wrapping. Puncture any surface bubbles with a greased toothpick.