Slice the mushrooms about ¼-inch thick. Heat 6 tablespoons of butter in a large skillet; add the mushrooms and ¼ teaspoon salt. Saute over medium heat, add half cup of dry white wine stirring frequently, add one cup of chicken broth until they are cooked through, 15 to 20 minutes.
In a large mixing bowl, combine the mushrooms, radicchio, cream, cheeses, sage.
Parboil the pasta shells for 4 minutes; drain and add to the ingredients in the mixing bowl. Toss to combine.
Divide the pasta mixture among 6 to 8 individual, shallow, ceramic gratin dishes (1 ½ to 2 cup capacity). Dot with the remaining 2 tablespoons of butter and bake until bubbly and brown on top, about 7 to 10 minutes.
Garnish with fresh Italian parsley, but do not cook the parsley in the pasta.