Heat oven to 350°F. Spray 11x7-inch (2-quart) or 13x9-inch (3-quart) glass baking dish with cooking spray. In medium bowl, mix potatoes, milk and soup; pour into baking dish. Bake uncovered 15 to 20 minutes or until bubbly and thickened.
Meanwhile, separate dough into 8 triangles. On wide end of triangles, evenly layer chicken and 1 cup of the cheese. Roll up, starting at wide end, gently wrapping dough around chicken mixture and rolling to opposite point. Carefully place rolls, point side down, over potato mixture.
Bake 20 to 25 minutes or until rolls are golden brown. Sprinkle with remaining 1 cup cheese and the bacon. Bake 2 to 4 minutes longer or until cheese is melted. Sprinkle with onions. Serve with sour cream.