Scrub potatoes, and pat dry; rub with oil, and wrap in aluminum foil.
Bake at 400° for 1 hour or until tender. Peel potatoes, discarding skins; mash pulp with a fork.
Beat potato pulp, 2 cups flour, and next 4 ingredients at medium speed with an electric mixer until blended.
Turn dough out onto a well-floured surface. Divide dough into 8 equal portions, and coat each portion with flour. Knead portions with well-floured hands until smooth and elastic and no longer sticky. Roll each portion into 3/4-inch diameter ropes; cut each rope into 3/4-inch lengths. Place dough pieces on floured baking sheets.
Bring 3 quarts water to a boil over medium-high heat in a large Dutch oven. Drop dough pieces, 10 to 12 at a time, into water, and cook 3 to 4 minutes or until gnocchi rises to the top.
Spread 1 cup Light Tomato Sauce in bottom of a lightly greased 13- x 9-inch baking dish; top with one-fourth of gnocchi, and sprinkle with 3/4 cup Parmesan cheese. Repeat layers 3 times with sauce, remaining gnocchi, and cheese, reserving remaining sauce for another use.
Bake at 350° for 20 to 30 minutes.
Note: Uncooked gnocchi may be frozen on a baking sheet, and stored in heavy-duty zip-top plastic bags in the freezer up to 2 months. Remove frozen gnocchi from freezer, and boil as directed 5 to 6 minutes. Casserole may be prepared a day ahead, and chilled. Let stand at room temperature 30 minutes before baking; bake at 350° for 30 to 45 minutes.