In a covered Dutch oven, cook the potatoes in a large amount of boiling water for 20 to 25 minutes or until tender; drain. Mash with potato masher or beat with an electric mixer on low speed until smooth; set aside.
In a small bowl, mix together bread crumbs, butter, and parsley. Press the mixture onto the bottom and up the side of a lightly greased 1-1/2-qt. casserole. Set aside.
In a medium bowl, slightly beat the egg yolks; stir in the 1/4 cup basil, shredded lemon peel, lemon juice, salt and pepper. Stir in milk and 1 cup of the cheese. Stir milk mixture into the mashed potatoes.
In a medium mixing bowl, beat the egg whites with an electric mixer on medium speed until stiff peaks form; fold into potato mixture.
Transfer to prepared casserole; top with remaining 1/2 cup cheese. Bake, uncovered, in a preheated 350-degree oven for 45 minutes or until a knife inserted in the center comes out clean. If desired, garnish with snipped basil and lemon peel strips.