In a large skillet over medium-high heat, melt butter. Add onions and sugar, and cook, stirring occasionally, until softened and browned (about 5 minutes). Add salt and pepper, reduce heat to medium, and cook until caramelized (10-15 minutes). Remove from heat and let cool to room temperature.

Preheat oven to 350°F. Spray a 9x13-inch baking dish with nonstick cooking spray. On a floured surface, unroll crescent dough into a large rectangle, pinching seams together. Top with provolone cheese, roast beef, and caramelized onions. Roll tightly from the long edge, and cut into 12 rolls. Place in the baking dish.

Bake rolls for 43-45 minutes, or until the dough is golden brown.

In a small, microwave-safe bowl, melt butter. Stir in salt and parsley. Brush the topping over the warm rolls before serving.