Pound chicken breasts between two sheets of plastic wrap until about 1/4 inch thick.
Place the milk, flour, beaten eggs and bread crumbs in separate shallow dishes. Add the Parmesan cheese to the bread crumbs and mix well. Season the eggs with a pinch of kosher salt.
Dip each breast in the following order: milk, flour, eggs, bread crumbs. Press down firmly while coating with bread crumbs.
In a large skillet, melt the butter with the olive oil over medium-high heat until sizzling. Arrange chicken breasts in the pan without crowding. Cook in batches if necessary. Reduce heat and cook chicken until golden brown and the juices run clear when pricked with a fork, approximately 3 to 5 minutes per side. Remove and pat off excess oil.
Place 1/2 cup of the warm tomato sauce in the bottom of a 9 x 13 x 2-inch baking dish. Add three of the cooked breasts to the baking dish; cover with 1/2 cup tomato sauce and half the mozzarella. Repeat with the remaining chicken breasts and sauce, and top with mozzarella.
Transfer to broiler and broil until the cheese is melted and golden brown, about 5 minutes. Remove and serve immediately over pasta al dente.
Makes: 6